Autoroute 20 is a Quebec Autoroute, following the Saint Lawrence River through one of the more densely populated parts of Canada, with its central section forming the main route of the Trans-Canada Highway from the A-25 interchange to the A-85 interchange. At 585 km (363.5 mi), it is the longest Autoroute in Quebec. It is one of two main links between Montreal and Quebec City; the other is the A-40.

There are two sections of the A-20, separated by a 57 km (35.4 mi) gap. The main segment extends for 540 km (335.5 mi) from the Ontario border to its current terminus at Trois-Pistoles. The second, more northerly section is far shorter (44 km (27.3 mi)), constructed as a super two autoroute (one lane in each direction), which bypasses Rimouski to the south and ends at a roundabout junction with Highway 132 in Mont-Joli. While the Quebec government has completed environmental and economic reviews of the impact of linking the two sections of Autoroute 20, it has not committed the funds necessary for construction. Citing the high number of accidents on the Rimouski-Mont-Joli link of the A-20, many politicians in the Bas-Saint-Laurent region have criticized the government's lack of progress in linking the two sections of autoroute and twinning the two-lane portion.

A-20 begins at the Ontario-Quebec border near Rivière-Beaudette as the continuation of Ontario Highway 401. The westernmost section of A-20 was named the Autoroute du Souvenir (Remembrance Highway) in 2007 to honour Canadian veterans. Road marker signs on this stretch of the autoroute feature a poppy (a traditional symbol of Remembrance in Canada).

At km 29, A-20 crosses A-30 (former A-540) before becoming an urban boulevard for approximately eight kilometres (km 30 to 38) in Vaudreuil-Dorion and L'Île-Perrot. This stretch of highway takes A-20 across the Ottawa River. The speed limit is 50 km/h (30 mph) in Vaudreuil-Dorion and 70 km/h (45 mph) in L'Île-Perrot. A-20 once again becomes a limited-access highway at km 38, just before crossing the Sainte-Anne-de-Bellevue Canal onto the Island of Montreal.

A-20 then traverses the West Island (in French, l'Ouest de l'Île) along the north shore of Lac Saint-Louis to an interchange with A-520. Commonly called the Dorval Interchange, this exit is the main access to Montreal's Trudeau International Airport. Further east, A-20 crosses the A-13 at its southern terminus, and then, at the St. Pierre Interchange, Route 138 west towards the Mercier Bridge.

Just west of downtown Montreal, A-20, A-15, and Route 136 meet at the Turcot Interchange. In 2020, the completion of a major project involving the rebuilding of the Turcot Interchange has shifted the autoroute north between Route 138 and the interchange. From there, A-20 east is multiplexed with A-15 south on the approach to the Samuel-de-Champlain Bridge.

Multiplexed with A-10 and A-15, all three autoroutes cross the Saint Lawrence River via the Samuel-de-Champlain Bridge to Longueuil. The multiplex splits south of the bridge. The A-20 parallels the south shore of the river through suburban Longueuil. The junction with A-25 affords a direct connection to the Louis Hippolyte Lafontaine Bridge-Tunnel and Montreal's East End. The Trans-Canada Highway joins A-20 at this junction.

The longest section of A-20 (from its junction with A-25 to its easternmost terminus) is named after Jean Lesage, who served as Premier of Quebec from 1960 to 1966, during the Quiet Revolution. Autoroute Jean-Lesage currently exists as two discontinuous sections separated by about 55 kilometres:

• The main section between the Louis-Hippolyte-Lafontaine Bridge-Tunnel and Trois-Pistoles in the Bas-Saint-Laurent region.
• A shorter section that serves as a bypass of Rimouski and extends east to a final terminus at Route 132 in Mont-Joli.

From the junction with A-25, A-20 travels east, away from the St. Lawrence River. At kilometre 98, A-20 intersects A-30 near Boucherville, crossing the Richelieu River (km 112) just north of Mont-Saint-Hilaire. Bypassing Saint-Hyacinthe, A-20 forms a multiplex with Route 116 for six kilometres between exits 141 and 147. This section of A-20 in Centre-du-Québec is located the furthest from the St. Lawrence River (approximately 45 kilometres). Between Drummondville and Sainte-Eulalie, A-20 forms a multiplex with A-55 for 37 kilometres.

A-20 continues across the Great Lakes–St. Lawrence Lowlands and Quebec's agricultural heartland. The autoroute once again parallels the river as it approaches metropolitan Quebec City. From this point eastward, A-20 is never more than five kilometres from the river. At km 312, A-20 crosses the A-73, a north–south link between Saint-Georges and Quebec City via the Pierre Laporte Bridge. While the control city on A-20 is listed as "Québec", the autoroute never enters the city proper. Before departing the region, the freeway bypasses suburban Lévis.

As it continues eastward, A-20 passes the regional centres of Montmagny and La Pocatière before approaching Rivière-du-Loup and the junction with A-85 at km 499. The Trans-Canada Highway departs A-20 at this interchange and travels southeast on A-85 toward Edmundston, New Brunswick and the Maritime Provinces. At km 518, the highway becomes a super two for the remainder of its main section. The eastern end of the main section of the A-20 is located in Trois-Pistoles, approximately 40 kilometres east of Rivière-du-Loup.

The second section of Autoroute Jean-Lesage (km 597 to km 641) connects Rimouski to Mont-Joli. It begins at a junction with Route 132 in Rimouski, approximately 55 km from the current terminus of A-20's main section. Like its larger counterpart, the Rimouski section of A-20 parallels the St. Lawrence, providing a southern bypass of Rimouski before ending (at another junction with Route 132) at the western approach to Mont-Joli.

This section of the A-20 is currently a single carriageway with occasional passing lanes. It was built to accommodate an eventual expansion to four lanes and most overpasses include the clearance needed to accommodate the additional lanes. The high accident rate along this section of A-20 have prompted many politicians to call for the highway to be expanded to two lanes in each direction.

An electric fence has been installed on both sides of the highway between km 621 and 628 to prevent moose from crossing the road, while at km 624 an underpass has been constructed to allow wildlife to pass under the highway safely.

Transports Québec (MTQ) is currently engaged in several projects designed to connect the two segments of A-20.

Long-range plans by the MTQ call for the two sections of A-20 to meet. A 9.8 km section of single carriageway was opened to traffic on December 3, 2011 between Cacouna and L'Isle-Verte. As part of this project, a few kilometres of the highway near Cacouna was moved 1.5 km to the south and the old roadbed was destroyed. The MTQ timeline for completing the highway to Trois-Pistoles was met; it opened to traffic in November 2015. Overpasses were constructed for the St-Paul, St-Éloi and Drapeau roads.

Regarding the section from Trois-Pistoles to Rimouski, the Quebec government has completed environmental and economic reviews of the impact of linking the two sections of Autoroute 20, but it has not committed the funds necessary for construction. Frustrated by the long delay in linking the two sections of A-20, in 2013, the Mayor of Rimouski proposed paying for the construction by tolling the autoroute.

Citing predictions for an increase in ferry traffic to and from the Côte-Nord as a result of the Government of Quebec's Plan Nord, in 2011 the Mayor of Matane called for the further extension of A-20 to his city.

Autoroute 20 serves as the backdrop to the popular 2002 Quebec film Québec-Montréal by Ricardo Trogi about seven twenty-something travellers driving between the two cities.

The Quebec French expression "à l'autre bout de la 20" (in English, at the other end of the 20) refers to Montreal when the speaker is in Quebec City, and to Quebec City when one is in Montreal.

Older Anglophone Montrealers sometimes still refer to the section of the A-20 west of the city as Highway 2-20 (or "The Two and Twenty"), but the Route 2 designation was dropped in the mid 1970s.

RCM	Location	km	mi	Old exit	New exit	Destinations	Notes
Vaudreuil-Soulanges	Rivière-Beaudette	0.0	0.0		—	Highway 401 west – Cornwall, Toronto	Continuation into Ontario
		0.9	0.56	Rivière-Beaudette Service Centre (eastbound)
		2.5	1.6		2	R-325 to R-338 – Rivière-Beaudette, Saint-Télesphore
	Saint-Zotique	5.3	3.3		6	69 Avenue
		9.2	5.7		9	Saint-Zotique, Saint-Polycarpe, Saint-Télesphore
	Les Coteaux	11.4	7.1		12	Les Coteaux
	Coteau-du-Lac	13.6	8.5		14	R-201 south – Pont Monseigneur-Langlois, Salaberry-de-Valleyfield	West end of R-201 concurrency
		16.4	10.2		17	R-201 north – Coteau-du-Lac, Saint-Clet	East end of R-201 concurrency
		18.6	11.6		19	Chemin Saint-Emmanuel
	Les Cèdres	21.5	13.4		22	Chemin Saint-Dominique
		25.0	15.5		26	Saint-Lazare, Les Cèdres
	Vaudreuil-Dorion	27.6	17.1		29	A-30 to A-40 – Sorel-Tracy, Ottawa/Gatineau, Montréal, Mirabel Airport	A-30 exit 5
		31.6	19.6		—	R-342 (Route Harwood)	At-grade intersection
		32.7	20.3		—	R-338 (Chemin de Lotbinière)	At-grade intersection
		33.3	20.7		—	Avenue Saint-Henri	At-grade intersection
	Ottawa River	33.7– 34.2	20.9– 21.3	Taschereau Bridge
	Pincourt	34.3	21.3		35	Boulevard Cardinal-Léger – Terrasse-Vaudreuil, Pincourt
		35.3	21.9		—	Boulevard de l'Île	At-grade intersection. Entrance and exit to south only.
	L'Île-Perrot	36.7	22.8		—	Boulevard Don-Quichotte	At-grade intersection
		37.2	23.1		—	Boulevard Perrot	At-grade intersection
		37.8	23.5		38	Chemin de L'Île-Claude, Rue de L'Île-Bellevue	Westbound exit and eastbound entrance
Ottawa River		38.1– 38.4	23.7– 23.9	Galipeault Bridge
Montréal	Sainte-Anne-de-Bellevue	38.5	23.9		39	Sainte-Anne-de-Bellevue
	Baie-D'Urfé	41.3	25.7		42	Rue Morgan
	Beaconsfield	43.8	27.2		45	Avenue Woodland
		47.2	29.3		48	Boulevard Saint-Charles
	Pointe-Claire	48.7	30.3		49	Avenue Cartier
		49.9	31.0		50	Boulevard Saint-Jean	Westbound signed as exits 50-S (south) and 50-N (north)
		51.5	32.0		51	Chemin du Bord-du-Lac	Eastbound exit and entrance
	Dorval	52.6	32.7		53	Boulevard des Sources
		53.8	33.4		54	Boulevard Pine Beach, Boulevard Fénelon
		54.9	34.1		56-E	A-520 east / Avenue Dorval – P.E. Trudeau Airport	Westbound signed as exit 56-E (east)
		55.5	34.5		56-O	Boulevard Romeo Vachon, P.E. Trudeau Airport	Westbound exit and eastbound entrance, Westbound signed as exit 56-O (west)
	Montréal	57.5	35.7		58	55 Avenue
		59.3	36.8		60	A-13 north / 32 Avenue – Laval, Mirabel Airport	A-13 exit 1
		61.0	37.9		61	Rue Norman	Westbound exit and entrance
		61.9	38.5		62	1 Avenue, Avenue Saint-Pierre, Avenue Dollard	Westbound exit via exit 63
		62.7	39.0		63	R-138 west – Pont Mercier	West end of R-138 concurrency; R-138 exit 4
		63.9	39.7		64	Rue Saint-Jacques (R-138 east) / Boulevard Angrignon	East end of R-138 concurrency
		65.1	40.5		67	Rue Notre Dame, Boulevard Angrignon	Eastbound exit via exit 64
		67.3	41.8		68 63	A-15 north (Autoroute Décarie) – Saint-Jérôme R-136 east (Autoroute Ville-Marie) – Montreal Centre-ville	Turcot Interchange; west end of A-15 concurrency; A-15 exit 63; exit numbers follow A-15
		69.4	43.1		62	Boulevard de la Vérendrye, Avenue de l'Église
		70.6	43.9		61	Rue Atwater, Rue Saint-Patrick
		71.8	44.6		60	To A-10 west / Boulevard Gaétan-Laberge, Rue Wellington – Montreal Centre-ville	A-10 exit 4; eastbound access to A-10 west (unsigned)
		74.0	46.0		58	A-10 west – Montreal Centre-ville, Île des Sœurs	Westbound exit and eastbound entrance; west end of A-10 concurrency; A-10 exit 5
					57	Boulevard de Île des Sœurs, Chemin de la Pointe Nord	Eastbound exit and westbound entrance; signed as 57-S (south) and 57N (north)
Saint Lawrence River		74.4– 77.2	46.2– 48.0	Champlain Bridge
Longueuil	Brossard	77.6– 79.1	48.2– 49.2		6 75	A-10 east to A-30 / I-89 – Sherbrooke, Québec, Vermont A-15 south / R-132 west to I-87 – La Prairie, New York	East end of A-10 / A-15 concurrency; west end of R-132 concurrency; eastbound signed as exit 6; westbound signed as exit 75; A-10 exit 6; A-15 north exit 53
					75	Boulevard Rome	Westbound exit; accessed from A-15 north / R-132 north exit 52
					—	Boulevard Marie-Victorin	Eastbound exit only
	Saint-Lambert	79.5	49.4	1	76	Boulevard Simard
		80.6	50.1	3	78	R-112 (Boulevard Laurier) – Pont Victoria, Montreal	Westbound signed as exits 78-O (west) and 78-E (east); eastbound access to R-112 west via exit 79
		82.9	51.5	6	79	Avenue Notre-Dame
	Longueuil	84.5	52.5	7	81	Boulevard Lafayette	Eastbound exit and entrance
		85.2	52.9	8	82	R-134 (Boulevard Taschereau) – Pont Jacques-Cartier, Montreal
		88.5	55.0	11	85	Boulevard Roland-Therrien
		92.5	57.5	15 90	89 90	A-25 (TCH) north to A-40 – Tunnel Louis-H.-Lafontaine, Montreal R-132 east – Boucherville, Varennes	Trans-Canada Highway west end (continues on A-25 north); east end of R-132 concurrency; eastbound signed as exits 89-N (north) and 89-E (east); westbound signed as exit 90
		92.7	57.6		90	Boulevard Marie-Victorin
		93.6	58.2		91	Boulevard Industriel, Rue Métropole
	Boucherville	94.3	58.6		92	Boulevard Mortagne
		95.1	59.1		93	Rue Nobel	Eastbound exit only
		98.0	60.9		95	Boulevard de Montarville
		99.0	61.5		98	A-30 to A-10 – Saint-Hubert Airport, Brossard, Sorel-Tracy, Châteauguay, USA	A-30 exit 83
Marguerite-D'Youville	Sainte-Julie	101.5	63.1		102	Sainte-Julie, Saint-Amable, Saint-Bruno-de-Montarville
		104.8	65.1		105	R-229 – Saint-Basile-le-Grand, McMasterville
La Vallée-du-Richelieu	Saint-Mathieu-de-Beloeil–Beloeil boundary	109.1	67.8		109	Rue Saint-Jean-Baptiste – Beloeil, Saint-Mathieu-de-Beloeil
	Beloeil	112.4	69.8		112	R-223 (Rue Richelieu) – Beloeil, Saint-Marc-sur-Richelieu
	Mont-Saint-Hilaire	112.8	70.1		113	R-133 (Chemin des Patriotes) – Mont-Saint-Hilaire, Saint-Jean-sur-Richelieu, Saint-Charles-sur-Richelieu
		115.5	71.8		115	La Grande-Allée – Saint-Jean-Baptiste, Saint-Damase
Les Maskoutains	Sainte-Madeleine	117.6	73.1	Sainte-Madeleine Rest Stop (eastbound) Hurons Rest Stop (westbound)
		119.8	74.4		120	R-227 – Sainte-Madeleine, Saint-Jean-Baptiste
	La Présentation	123.1	76.5		123	Grand Rang – La Présentation, Saint-Hyacinthe
	Saint-Hyacinthe	128.6	79.9		128	Avenue Pinard
		130.6	81.2		130	R-137 / R-235 – Saint-Hyacinthe, Granby, Saint-Denis-sur-Richelieu	Signed as exits 130S (south) and 130N (north)
		130.9	81.3	At-grade railway level crossing
		133.6	83.0		133	Rue Girouard – Saint-Hyacinthe
		134.0	83.3		134	Rue Yamaska – Saint-Hyacinthe
		137.9	85.7		138	R-224 – Saint-Hyacinthe, Saint-Simon
	Saint-Simon	141.7	88.0		141	R-116 west to R-137 south – Saint-Hyacinthe, Granby	West end of R-116 concurrency
		142.5	88.5		143	R-211 to Saint-Valérien-de-Milton
	Saint-Simon–Saint-Liboire boundary	145.0	90.1		145	Saint-Simon, Saint-Liboire
		146.4	91.0		147	R-116 east – Upton, Acton Vale	East end of R-116 concurrency
	Sainte-Hélène-de-Bagot	150.3	93.4		150	Saint-Hugues
		152.4	94.7		152	Sainte-Hélène-de-Bagot
Acton–Drummond boundary	Saint-Nazaire-d'Acton–Saint-Eugène boundary	156.1	97.0	Saint-Nazaire-d'Acton Rest Stop (westbound)
		156.9	97.5		157	Saint-Nazaire-d'Acton, Wickham
Drummond	Saint-Eugène	160.6	99.8		160	R-239 – Saint-Eugène, Saint-Guillaume
	Saint-Germain-de-Grantham	165.7	103.0		166	10 Rang de Saint-Germain-de-Grantham
		170.3	105.8		170	R-122 – Saint-Germain-de-Grantham, Yamaska, Sorel-Tracy
	Drummondville	173.7	107.9		173	A-55 south to I-91 – Drummondville, Sherbrooke, Vermont	West end of A-55 concurrency; A-55 exit 128
		174.2	108.2		175	R-143 north (Boulevard Lemire) – Saint-Bonaventure, Saint-François-du-Lac	West end of R-143 concurrency
		177.0	110.0		177	R-143 south – Saint-Majorique-de-Grantham, Drummondville	East end of R-143 concurrency
		179.3	111.4		179	Chemin du Golf
		180.8	112.3		181	Drummondville
	Saint-Cyrille-de-Wendover	185.6	115.3		185	R-255 – Baie-du-Febvre, Saint-Cyrille-de-Wendover, Saint-Félix-de-Kingsey
	Notre-Dame-du-Bon-Conseil	191.6	119.1		191	Sainte-Brigitte-des-Saults
		196.5	122.1		196	R-259 – Nicolet, Sainte-Perpétue, Notre-Dame-du-Bon-Conseil, Quebec
Drummond–Nicolet-Yamaska boundary	Notre-Dame-du-Bon-Conseil–Saint-Léonard-d'Aston boundary	199.8	124.1		200	Saint-Léonard-d'Aston	Former R-155 north
Nicolet-Yamaska	Saint-Léonard-d'Aston	201.8	125.4		202	Rang du Moulin-Rouge
	Sainte-Eulalie	203.0	126.1		204	Rang des Cédres, Rang des Plaines
		208.0– 211.0	129.2– 131.1		210	A-55 north – Bécancour, Trois-Rivières A-955 south – Victoriaville, Saint-Albert, Warwick R-161 – Sainte-Eulalie, Saint-Valère	East end of A-55 concurrency; A-55 exit 145; A-955 exit 15
		214.7	133.4		215	Rang des Épinettes
Arthabaska	Daveluyville	220.3	136.9		220	R-261 – Bécancour, Daveluyville, Victoriaville
		223.0– 225.0	138.6– 139.8	Daveluyville Rest Stop (eastbound) Lac-à-la-Truite Rest Stop (westbound)
	Saint-Louis-de-Blandford	228.7	142.1		228	R-165 (2 Rang de Saint-Louis-de-Blandford) – Princeville, Plessisville, Thetford Mines
		235.0	146.0		235	R-162 south / R-263 north – Lemieux, Princeville, Victoriaville, Saint-Louis-de-Blandford
Bécancour	Manseau	243.6	151.4		243	R-218 – Manseau, Saint-Pierre-les-Becquets
L'Érable	Villeroy	252.6	157.0		253	R-265 – Villeroy, Plessisville, Deschaillons-sur-Saint-Laurent, Notre-Dame-de-Lourdes, Thetford Mines
		254.0	157.8	L'Érable Rest Stop (eastbound) Villeroy Rest Stop (westbound)
		256.4	159.3		256	15 et 16 Rangs de Villeroy
Lotbinière	Val-Alain	261.7	162.6		261	Val-Alain
		266.5	165.6		266	4 et 5 Rangs de Val-Alain
	Saint-Janvier-de-Joly	271.6	168.8		271	Saint-Janvier-de-Joly
	Laurier-Station	278.1	172.8		278	R-271 – Laurier-Station, Sainte-Croix, Saint-Flavien
	Saint-Apollinaire	284.8	177.0		285	Notre-Dame-du-Sacré-Cœur-d'Issoudun
		290.7	180.6		291	R-273 – Saint-Agapit, Saint-Apollinaire, Saint-Antoine-de-Tilly
		296.3	184.1		296	Route du Cap
Lévis		305.3	189.7		305	R-171 – Lévis, Thetford Mines
		309.0	192.0	Chaudière-Appalaches Service Centre (eastbound)
		311.4	193.5		311	R-116 – Lévis
		312.8– 314.0	194.4– 195.1		312	A-73 to US 201 – Pont Pierre-Laporte, Québec, Saint-Georges, Maine	Signed as exits 312S (south) and 321N (north); westbound exit is part of 314; A-73 exit 131
					314	R-175 – Pont de Québec, Lévis
		317.9	197.5		318	R-275 – Lévis	Eastbound signed as exits 318-S (south) and 318-N (north)
		321.5	199.8		321	Chemin des Îles
		325.0	201.9		325	R-173 to R-277 – Lac-Etchemin, Lévis	Eastbound signed as exits 325-S (south) and 325-N (north)
		327.5	203.5		327	Route Monseigneur-Bourget
		330.5	205.4		330	Route Lallemand
Bellechasse	Beaumont	337.3	209.6		337	R-279 – Beaumont, Saint-Charles-de-Bellechasse, Saint-Damien-de-Buckland
		341.0	211.9		341	Beaumont, Saint-Charles-de-Bellechasse
	Saint-Michel-de-Bellechasse	344.0– 345.0	213.8– 214.4	La Durantaye Rest Stop (eastbound) Saint-Michel-de-Bellechasse Rest Stop (westbound)
		348.0	216.2		348	R-281 – Saint-Michel-de-Bellechasse, La Durantaye
	Saint-Vallier	355.7	221.0		356	Saint-Vallier, Saint-Raphaël
Montmagny	Berthier-sur-Mer–Saint-François-de-la-Rivière-du-Sud boundary	363.9	226.1		364	Berthier-sur-Mer, Saint-François-de-la-Rivière-du-Sud
	Saint-François-de-la-Rivière-du-Sud–Montmagny boundary	369.3	229.5		369	Saint-Pierre-de-la-Rivière-du-Sud
	Montmagny	375.9	233.6		376	R-228 (Chemin des Poirier) – Montmagny
		377.6	234.6		378	R-283 – Montmagny, Saint-Fabien-de-Panet
	Cap-Saint-Ignace	388.3	241.3		388	Cap-Saint-Ignace
L'Islet	L'Islet	393.0	244.2	Belles-Amours Rest Stop (westbound, seasonal)
		399.9	248.5		400	R-285 – L'Islet
	Saint-Jean-Port-Joli	413.5	256.9		414	R-204 – Saint-Jean-Port-Joli, Saint-Aubert, Saint-Pamphile
	Saint-Roch-des-Aulnaies	430.0	267.2		430	R-132 – Saint-Roch-des-Aulnaies, Sainte-Louise
Kamouraska	Sainte-Anne-de-la-Pocatière	435.8	270.8		436	R-132 (Avenue Industrielle) – La Pocatière
	La Pocatière	438.9	272.7		439	La Pocatière, Saint-Onésime-d'Ixworth
		443.8	275.8		444	R-132 (Avenue de la Grande-Anse) – La Pocatière, Rivière-Ouelle
	Rivière-Ouelle–Saint-Pacôme boundary	449.3	279.2		450	Rivière-Ouelle, Saint-Pacôme, Saint-Gabriel-Lalemant
	Saint-Philippe-de-Néri	455.7	283.2		456	R-287 – Saint-Denis-De La Bouteillerie, Saint-Philippe-de-Néri, Mont-Carmel
		458.0	284.6	Kamouraska Rest Stop (westbound) Monadnocks Rest Stop (eastbound)
	Saint-Pascal	464.4	288.6		465	Kamouraska, Saint-Pascal, Saint-Bruno-de-Kamouraska
	Sainte-Hélène-de-Kamouraska	473.9	294.5		474	Saint-Germain-de-Kamouraska, Sainte-Hélène-de-Kamouraska
	Saint-André-de-Kamouraska	479.9	298.2		480	Saint-André-de-Kamouraska, Saint-Joseph-de-Kamouraska
	Saint-André-de-Kamouraska–Saint-Alexandre-de-Kamouraska boundary	487.5	302.9		488	R-289 to R-230 – Saint-Alexandre-de-Kamouraska, Pohénégamook, Lac-Baker, NB
Rivière-du-Loup	Notre-Dame-du-Portage	495.1	307.6		496	Notre-Dame-du-Portage
		498.0	309.4	Portage Rest Stop (eastbound, seasonal)
		499.3	310.3		499	A-85 (TCH) south to R-185 / Route 2 – Témiscouata-sur-le-Lac, Dégelis, New Brunswick	Trans-Canada Highway east end (continues on A-85 south); eastbound exit and westbound entrance; A-85 exit 100
	Rivière-du-Loup	502.3	312.1		503	R-132 (Rue Fraser) / Boulevard de l'Hôtel-de-Ville
		506.6	314.8		507	R-132 (Boulevard Cartier) – Saint-Siméon
	Cacouna	513.9	319.3		514	R-191 to A-85 – Saint-Arsène, Cacouna, Témiscouata-sur-le-Lac, New Brunswick	Westbound access to A-85
		520.5	323.4		521	Route Moreault
	L'Isle-Verte	527.1	327.5		527	Montée des Coteaux
		531.4	330.2		531	L'Isle-Verte (Rue Notre-Dame), St-Paul-de-la-Croix
Rivière-du-Loup–Les Basques boundary	L'Isle-Verte–Saint-Éloi boundary	539.1	335.0		539	Saint-Éloi, Route de la Station
Les Basques	Notre-Dame-des-Neiges	542.5	337.1		542	To R-132 / Route Drapeau – Trois-Pistoles, Rimouski	Current eastern end of main segment
55 km (35 mi) gap in A-20
Rimouski-Neigette	Rimouski	0.0	0.0		—	R-132 – Rivière-du-Loup, Rimouski	At-grade intersection
		9.0	5.6		606	Rue de Lausanne
		13.4	8.3		610	R-232 (Chemin Sainte-Odile) – Rimouski
		17.4	10.8		614	Montée Industrielle-et-Commercialle
		24.5	15.2		621	Avenue Père-Nouvel / Rue de la Gare
La Mitis	Sainte-Luce	32.1	19.9		629	R-298 – Sainte-Luce, Saint-Donat, Sainte-Flavie6
	Mont-Joli	45.2	28.1		641	R-132 / Boulevard Jacques-Cartier – Sainte-Flavie, Matane, Amqui, New Brunswick	Eastern terminus; traffic circle
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access       Route transition

Other than the Rivière-Beaudette Rest Area, the remaining rest areas along A-20 are not full service and merely places for motorists and truckers to rest. Only some have washrooms and a few are seasonal.

There are 15 rest stops located at the following points along Autoroute 20, and contain the following services:

Location	Name	km	Direction	Services
Rivière-Beaudette	Rivière-Beaudette	2	Eastbound	Full Service Centre: Phone, Tourist Information, Washrooms C-store (Couche-Tard) Fuel (Esso) Food (St-Hubert, Tim Hortons) Electric vehicle charging station.
Sainte-Marie-Madeleine	Sainte-Madeleine	117	Eastbound	Phone, Washrooms
	Hurons		Westbound	Phone, Washrooms
Saint-Eugène	Saint-Nazaire-d'Acton	156	Westbound	Phone, Washrooms
Daveluyville	Daveluyville	223	Eastbound	Phone, Washrooms
	Lac-à-la-Truite	225	Westbound	Phone, Washrooms
Villeroy	L'Érable	254	Eastbound	Truck rest area. Driveway to washroom is blocked off and road signage indicating it is closed. Washrooms no longer available. Phones and food vendor removed. Motors can use next exit to the east to turn around to use Eastbound rest area (and travel to again to next to the west to return to eastbound route.)
	Villeroy		Westbound	Phone, Washrooms
Lévis	Chaudière-Appalaches (Formerly Saint-Rédempteur)	309	Eastbound	Phone, Tourist information, Vending machines and indoor seating with tables, Washrooms. Modern rest area building open 24 hours. Electric vehicle charging stations.
Saint-Michel-de-Bellechasse	La Durantaye	344	Eastbound	Phone, Vending machines, Washrooms
	Saint-Michel-de-Bellechasse	345	Westbound	Phone, Toursit Information, vending machines with tables and microwave oven, washrooms. Modern rest area building open 24 hours.
L'Islet	Belles-Amours	393	Westbound	Seasonal (Open only June to August): Phone, Vending machines, Washrooms
Saint-Philippe-de-Néri	Kamouraska	458	Eastbound	Phone, Vending machines, Washrooms
	Monadnocks		Westbound	Phone, Vending machines, Washrooms
Notre-Dame-du-Portage	Portage	498	Eastbound	Seasonal (Open only June to August): Phone, Tourist information, Washrooms located in house like structure.

A-20 eastbound

• 
  former 14th Ave. exit, Montréal, 2005
• 
  Merge with 138, Montréal, 2005
• 
  Turcot yards, 2005
• 
  Autoroute 20 eastbound, km 311 near Pierre-Laporte Bridges in Lévis, Québec

A-20 westbound

• 
  Autoroute 20 west, ~km59 on Montreal Island
• 
  Autoroute 20 east, near Rivière Beaudette, ~km 5
• 
  A-30 at A-20 westbound
• 
  Autoroute 20 west, exit 29.

• List of bridges in Montreal
• List of crossings of the Ottawa River
• List of crossings of the Saint Lawrence River

• A-20 at motorways-exits.com
• A-20 at Quebec Autoroutes
• Transports Quebec Map Archived 2008-05-17 at the Wayback Machine (in French)
• Veteran from Gaspé behind idea to rename Quebec highway to remember war dead
• Autoroute 20 @ Asphaltplanet.ca

Trans-Canada Highway
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