U.S. Route 1 (US 1) in the U.S. state of Maine is a major north–south section of the United States Numbered Highway System, serving the eastern part of the state. It parallels the Atlantic Ocean from New Hampshire north through Portland, Brunswick, and Belfast to Calais, and then the St. Croix River and the rest of the Canada–United States border via Houlton to Fort Kent. The portion along the ocean, known as the Coastal Route, provides a scenic alternate to Interstate 95 (I-95).

US 1 enters Maine from New Hampshire by bridging the Piscataqua River at Kittery on the Memorial Bridge. Following the sandy southern Maine coast, the highway bridges the Cape Neddick River in Cape Neddick; the Josias and Ogunquit rivers in Ogunquit; the Webhannet River in Wells; and the Merriland, Mousam, and Kennebunk rivers in Kennebunk. After bridging the Saco River between Biddeford and Saco, the highway bridges the Nonesuch River in Scarborough.

In South Portland, US 1 merges with I-295 at exit 4 and continues north through downtown Portland to Tukey's Bridge, now on I-295, before separating at exit 9. The Charles Loring Highway is part of US 1 in Portland. Like Loring Air Force Base, it is named for Charles J. Loring Jr.

North of Portland, the highway bridges the Presumpscot River (via the Martin's Point Bridge) in Falmouth, the Royal River in Yarmouth, and the Cousins River in Freeport before following the Androscoggin River through Brunswick and crossing the Kennebec River on the Sagadahoc Bridge between Bath and Woolwich. The section between Brunswick (at its junction with US 201) and Bath is a four-lane freeway, and the route continues as a four-lane expressway through most of Bath, then crosses on a two-lane viaduct before becoming four lanes again on the bridge over the Kennebec River. It then becomes a three-lane road (with center turning lane) through Woolwich and then reverts to two lanes after that as it continues north toward Wiscasset.

The highway bridges the Sheepscot River in Wiscasset, the Damariscotta River in Damariscotta, the Medomak River in Waldoboro, and the Saint George River in Thomaston before reaching Rockland.

In Rockland, there is a bypass of downtown (US 1A) which travels along Broadway and Maverick streets, while US 1 itself has a one way pair with Main and Union streets in the downtown Rockland area (Main Street traffic goes north with two lanes, while Union Street traffic is southbound).

The highway follows the coast of Penobscot Bay bridging the Goose River in Rockport, the Ducktrap River in Lincolnville, the Little River in Northport, and the Passagassawakeag River in Belfast before bridging the Penobscot River at Bucksport. The Atlantic coast is less frequently visible as the highway bridges the Orland River in Orland, the Union River in Ellsworth, Sullivan Harbor in Sullivan, the Narraguagus River in Cherryfield, the Harrington River in Harrington, the Pleasant River at Columbia Falls, the Indian River in Addison, and the Chandler River in Jonesboro.

After bridging the East Machias and Machias rivers in Machias, the highway turns inland along Passamaquoddy Bay to bridge the Orange River in Whiting, the Dennys River in Dennysville, and the Pennamaquan River in Pembroke. The highway then follows the St. Croix River through Calais and turns inland at Woodland. The interior route bridges Grand Falls Flowage at Princeton, the Meduxnekeag River in Houlton, the North Branch Meduxnekeag River in Monticello, and the Aroostook River in Presque Isle before following the Saint John River upstream from Van Buren to Fort Kent.

From Madawaska to its "northern" terminus at the Clair–Fort Kent Bridge in Fort Kent, US 1 north actually travels geographically south. The route's most northerly geographic point is at its intersection with the Edmundston–Madawaska Bridge in Madawaska, across the Saint John River from Edmundston, New Brunswick, Canada.

US 1 south of Calais was initially part of the Atlantic Highway and became Route 1 when the New England road marking system was established in 1922. The northward continuation from Calais was later designated as part of Route 24. In the original plan, Route 24 was to run from Brunswick to Moosehead Lake in Greenville. By 1925, however, Maine had transferred the Route 24 designation to a completely new alignment on the eastern edge of the state, running from Calais to Madawaska at a border crossing with Edmundston, New Brunswick.

The initial 1925 plan for the U.S. Route system took US 1 along the better-quality inland route (then Route 15) between Bangor and Houlton, and placed US 2 on the coastal route. This changed in the final 1926 plan, when the inland shortcut—now generally followed by I-95—became part of US 2.

The Waldo–Hancock Bridge opened in 1931, allowing US 1 to bypass Bangor; the old route became US 1A.

The portion between Portland and Brunswick was rebuilt, mainly as a four-lane divided highway, in the 1950s, and later absorbed into I-95 (now I-295). A freeway from Brunswick east to Bath was built in the 1960s.

County	Location	mi	km	Destinations	Notes
York	Kittery	0.00	0.00	US 1 south – Portsmouth	Continuation from New Hampshire over the Piscataqua River
		0.58	0.93	SR 103 – Eliot, Navy Yard, Kittery Foreside
		1.51	2.43	SR 236 to I-95 south (Maine Turnpike) / US 1 Byp. south – Kittery Point, New Hampshire, Massachusetts	Rotary; southern end of southbound concurrency with SR 236
		1.70	2.74	SR 236 north – South Berwick, Eliot	Northern end of southbound concurrency with SR 236
		1.79	2.88	US 1 Byp. south – New Hampshire, Massachusetts	Southbound left exit and northbound left entrance; northern terminus of US 1 Byp.
		2.07	3.33	I-95 / Maine Turnpike – Portland, Augusta, Portsmouth, Boston	Exit 3 on I-95 / Turnpike
		2.39	3.85	SR 101 north – Eliot	Southern terminus of SR 101
	York	6.72	10.81	SR 91 north – South Berwick	Southern terminus of SR 91
		7.09	11.41	US 1A north – York Village, York Harbor, York Beach	Southern terminus of US 1A
		7.43	11.96	I-95 / Maine Turnpike	Exit 7 on I-95 / Turnpike; access via Spur Road
		10.69	17.20	US 1A south	Northern terminus of US 1A
	Wells	18.28	29.42	SR 9B west – North Berwick, Berwick	Eastern terminus of SR 9B
		20.27	32.62	SR 9 west / SR 109 north to I-95 / Maine Turnpike – Sanford	Southern end of concurrency with SR 9; southern terminus of SR 109
		22.12	35.60	SR 9 east – Kennebunkport, Kennebunk	Northern end of concurrency with SR 9
	Kennebunk	25.10	40.39	SR 9A west / SR 99 west – Sanford	Southern end of concurrency with SR 9A; eastern terminus of SR 99
		25.46	40.97	SR 35 north to I-95 / Maine Turnpike	Southern end of wrong-way concurrency with SR 35
		25.50	41.04	SR 9A east / SR 35 south – Kennebunkport	Northern end of concurrency with SR 9 / SR 35
	Biddeford	31.79	51.16	To I-95 / Maine Turnpike / SR 111	Biddeford Connector
		32.94– 33.01	53.01– 53.12	SR 111 to I-95 / Maine Turnpike – Biddeford Pool, Alfred	Brief concurrency with SR 111
	Saco	34.93	56.21	SR 5 north / SR 112 to SR 9 – Bar Mills, Buxton	Southern end of wrong-way concurrency with SR 5
		35.82	57.65	SR 5 south – Old Orchard Beach	Northern end of wrong-way concurrency with SR 5
		35.91	57.79	I-195 to I-95 / Maine Turnpike	No exit to I-195 east; Exit 2 on I-195
		38.54	62.02	SR 98 east – Old Orchard Beach	Western terminus of SR 98
Cumberland	Scarborough	40.64	65.40	SR 9 west (Pine Point Road) – Old Orchard Beach	Southern end of concurrency with SR 9
		43.73	70.38	SR 207 south – Prouts Neck SR 114 north – Gorham	Northern terminus of SR 207 Southern terminus of SR 114
		44.89	72.24	To I-95 / Maine Turnpike / I-295 north – Portland	Interchange; eastbound exit and westbound entrance; access via SR 701
	South Portland	46.26	74.45	To I-95 / Maine Turnpike / I-295 north	Access via SR 703
		46.39	74.66	SR 9 east – South Portland	Northern end of concurrency with SR 9
		47.97	77.20	Veterans Memorial Bridge to US 1A – Portland Waterfront	Interchange; northbound exit and southbound entrance
		48.40	77.89	I-295 south – South Portland, Scarborough	Southbound exit and northbound entrance; southern end of concurrency with I-295; Exit 4 on I-295 south
	South Portland–Portland line	48.56	78.15	Fore River
	Portland	49.32	79.37	SR 22 / US 1A (Congress Street)	I-295 Exit 5; signed as Exits 5A (east) and 5B (west) southbound
		50.21	80.81	SR 100 south (Forest Avenue)	I-295 Exit 6A; US 1 removed from Forest Avenue in May 2007
				SR 100 north (Forest Avenue) / US 302 west	I-295 Exit 6B
		50.75	81.67	US 1A (Franklin Street)	I-295 Exit 7
		51.43	82.77	SR 26 south (Washington Avenue)	I-295 Exit 8; southbound signage; southbound exit and northbound entrance; southern end of concurrency with SR 26
		51.59	83.03	SR 26 north (Washington Avenue)	I-295 Exit 8; northbound signage; northbound exit and southbound entrance; northern end of concurrency with SR 26
		51.83	83.41	US 1 south / SR 26 north (Washington Avenue) / Baxter Boulevard	I-295 Exit 9; southbound signage; southbound exit and northbound entrance; US 1 removed from Baxter Boulevard in May 2007
		51.99	83.67	I-295 north – Falmouth, Brunswick	Northbound exit and southbound entrance; northern end of concurrency with I-295; Exit 9 on I-295 north
	Portland–Falmouth line	52.65	84.73	Martin Point Bridge over the Presumpscot River
	Falmouth	54.03	86.95	SR 88 north	Southern terminus of SR 88
		55.22	88.87	Bucknam Road to I-295
		55.54	89.38	I-495 west (Falmouth Spur) to I-95 / Maine Turnpike – Lewiston, Kittery
	Cumberland	58.63	94.36	Tuttle Road to SR 88 – Cumberland Center, Cumberland Foreside	Grade-separated intersection
	Yarmouth	59.78– 59.95	96.21– 96.48	I-295 – Freeport, Portland	Exit 15 on I-295
		61.04	98.23	SR 115	Interchange
		61.98	99.75	SR 88 south – Falmouth	Northern terminus of SR 88
		62.07– 62.25	99.89– 100.18	I-295 – Brunswick, Portland	Exit 17 on I-295
	Freeport	65.63	105.62	Desert Road to I-295 – Brunswick, Augusta, Portland	Exit 20 on I-295
		67.17	108.10	SR 125 north / SR 136 north to I-295 – Durham
		68.70	110.56	I-295 north	Exit 24 on I-295
	Brunswick	73.93	118.98	I-295 – Freeport, Portland, Topsham, Augusta	Rotary
		75.74	121.89	SR 24 south (Maine Street) / SR 123 south – Harpswell	Northbound signage; southern end of limited-access segment
				US 201 north / SR 24 north – Topsham	Southbound signage
		76.42	122.99	SR 196 west to SR 24 / I-295 – Topsham, Lewiston	Eastern terminus of SR 196, Southern end of wrong-way concurrency with SR 24
		78.50	126.33	SR 24 – Cook's Corner, Brunswick Executive Airport, Orr's-Bailey Islands	Northern end of wrong-way concurrency with SR 24
Cumberland–Sagadahoc county line	Brunswick–West Bath line	81.16	130.61	New Meadows River
Sagadahoc	West Bath	81.32	130.87	New Meadows Road – West Bath
	Bath	82.98	133.54	Congress Avenue / Richardson Street – Bath	Richardson street only appears on northbound signage; Bath only appears on southbound signage
		83.57	134.49	SR 209 south – Phippsburg	Northbound signage; northern terminus of SR 209
		84.15	135.43	To SR 209 south – Phippsburg, Bath	Southbound signage; access to Visitor Center
	Bath–Woolwich line	84.29	135.65	Sagadahoc Bridge over the Kennebec River
	Woolwich	84.64	136.21	SR 127 south – Georgetown, Reid State Park, Arrowsic	Southern end of concurrency with SR 127; northern end of limited-access segment
		84.93	136.68	SR 127 north	Northern end of concurrency with SR 127
Lincoln	Wiscasset	90.73	146.02	SR 144 – Westport
		94.03	151.33	SR 27 north – Augusta, Gardiner	Southern end of wrong-way concurrency with SR 27
		94.31	151.78	SR 218
	Wiscasset–Edgecomb line	94.73	152.45	Sheepscot Bridge over the Sheepscot River
	Edgecomb	95.92	154.37	SR 27 south – Boothbay, Boothbay Harbor	Northern end of wrong-way concurrency with SR 27
	Newcastle	101.12	162.74	US 1 Bus. to SR 129 / SR 130 / SR 215 – Pemaquid Point, Pemaquid Beach, Damariscotta, Bristol	Interchange; northbound exit and southbound entrance; southern terminus of US 1 Bus
		102.11	164.33	SR 215 – Newcastle, Damariscotta, Damariscotta Mills	Interchange; southbound exit and northbound entrance
	Damariscotta	104.03	167.42	US 1 Bus. – Bristol, South Bristol, Pemaquid, Pemaquid Point, Pemaquid Beach, Damariscotta	Northern terminus of US 1 Bus
	Waldoboro	111.58	179.57	SR 32 – Waldoboro, Bremen, Jefferson
		112.42	180.92	SR 220 – Friendship, Washington
		113.34	182.40	SR 235 – Union, Hope
Knox	Warren	118.01	189.92	SR 90 east – Camden, Rockport	Western terminus of SR 90
		121.21	195.07	SR 97 (Cushing Road) – Friendship
	Thomaston	122.36	196.92	SR 131 north – Union	Southern end of wrong-way concurrency with SR 131
		124.13	199.77	SR 131 south – St. George	Northern end of wrong-way concurrency with SR 131
	Rockland	127.15	204.63	US 1A (Broadway)	Southern terminus of US 1A
		127.60	205.35	SR 73 south	Northern terminus of SR 73
		128.66	207.06	US 1A / SR 17 (Maverick Street) – Thomaston, Union	Northern terminus of US 1A
	Rockport	133.83	215.38	SR 90 west – Warren	Eastern terminus of SR 90
	Camden	135.77	218.50	SR 105 – Hope, Appleton
		135.98	218.84	SR 52 – Lincolnville Center
Waldo	Lincolnville	141.59	227.87	SR 173 (Beach Road / McKay Road)
	Belfast	153.89	247.66	SR 52 – Lincolnville Center
		154.30	248.32	SR 3 west – Belfast, Augusta	Interchange; southern end of concurrency with SR 3
		154.80– 155.11	249.13– 249.63	SR 7 / SR 137 – Belfast, Brooks, Freedom	Interchange; southbound exit and northbound entrance via High Street
		155.32	249.96	Passagassawakeag River
		155.60	250.41	SR 141 – Swanville
	Stockton Springs	165.03	265.59	US 1A – Winterport, Bangor	Southern terminus of US 1A
	Prospect	171.14	275.42	SR 174 – Fort Knox
Waldo–Hancock county line	Prospect–Verona Island line	171.33	275.73	Penobscot Narrows Bridge over the Penobscot River
Hancock	Bucksport	172.71	277.95	SR 15 north – Bucksport, Bangor	Southern end of wrong-way concurrency with SR 15
	Orland	173.86	279.80	SR 46 – Dedham, East Holden
		174.48	280.80	SR 175 – Orland, Castine
		177.11	285.03	SR 15 south – Penobscot, Blue Hill, Deer Isle	Northern end of wrong-way concurrency with SR 15
		181.29	291.76	SR 176 – Surry
	Ellsworth	191.65	308.43	SR 172 – Blue Hill, Surry
		191.85	308.75	SR 230 (Water Street)
		192.13	309.20	US 1A – Bangor	Northern terminus of US 1A
		193.16	310.86	SR 3 east – Bar Harbor, Acadia National Park	Northern end of concurrency with SR 3
		194.03	312.26	SR 184 – Lamoine
	Hancock	197.86	318.42	SR 182 – Cherryfield
	Sullivan	204.32	328.82	SR 200 – Franklin
		205.31	330.41	SR 185 – Sorrento
		206.90	332.97	SR 183 – Tunk Lake
	Gouldsboro	210.35	338.53	SR 186 – Winter Harbor, Birch Harbor
		211.60	340.54	SR 195 – Prospect Harbor, Corea
		213.51	343.61	SR 186 – Prospect Harbor, Winter Harbor, Birch Harbor
Washington	Milbridge	223.81	360.19	US 1A – Calais, Machias, Harrington	Southern terminus of US 1A
	Cherryfield	228.78	368.19	SR 182 – Franklin, Ellsworth
		228.95	368.46	SR 193 – Deblois
	Harrington	235.54	379.06	US 1A – Milbridge, Ellsworth	Northern terminus of US 1A
	Columbia Falls	241.13	388.06	SR 187 – Addison, Jonesport, Beals
	Jonesboro	246.97	397.46	SR 187 – Jonesport, Beals Island
		250.08	402.46	US 1A – Whitneyville	Southern terminus of US 1A
	Machias	255.77	411.62	SR 92 – Machiasport
		255.92	411.86	SR 192 (Colonial Way) – Wesley
		256.34	412.54	US 1A – Whitneyville	Northern terminus of US 1A
	East Machias	260.15	418.67	SR 191 north – Baring Plantation	Southern end of wrong-way concurrency with SR 191
		260.24	418.82	SR 191 south – Cutler	Northern end of wrong-way concurrency with SR 191
	Whiting	272.87	439.14	SR 189 – Lubec
	Dennysville	282.27	454.27	SR 86 – Dennysville
	Pembroke	286.72	461.43	SR 214 – Meddybemps
	Perry	293.32	472.05	SR 190 – Pleasant Point, Eastport
	Calais	313.82	505.04	SR 9 east – St. Stephen NB, International Bridge	Southern end of concurrency with SR 9
		316.00	508.55	International Avenue to Route 1 – St. Stephen, St. John
	Baring	319.48	514.15	SR 191 – Machias
	Baileyville	320.73	516.16	SR 9 west – Bangor	Northern end of concurrency with SR 9
	Topsfield	350.08	563.40	SR 6 – Lincoln, Vanceboro, St. Croix NB, Springfield
	Danforth	370.51	596.28	SR 169 – Prentiss, Springfield
Aroostook	Houlton	404.43	650.87	US 2 east – Woodstock NB	Southern end of concurrency with US 2
		404.50	650.98	US 2A – Bangor
		404.79	651.45	US 2 west – Island Falls	Northern end of concurrency with US 2
		405.54– 405.68	652.65– 652.88	I-95 – New Brunswick, Canada, Bangor	Exit 302 on I-95
	Mars Hill	432.00	695.24	US 1A – Fort Fairfield	Southern terminus of US 1A
	Presque Isle	446.24	718.15	SR 10 – Easton
		446.87	719.17	SR 167 – Fort Fairfield
		447.73	720.55	SR 163 to SR 167 / SR 227 – Fort Fairfield, Ashland
		448.07	721.10	SR 164 – Washburn
	Caribou	455.76	733.47	SR 164 to SR 228 – Caribou
		458.63	738.09	SR 161 south / SR 161B (Fort Street) – Fort Fairfield	Southern end of concurrency with SR 161
		459.20	739.01	SR 89 west to SR 164 / SR 228 / SR 161B – Caribou	Southern end of concurrency with SR 89
		459.67	739.77	SR 161 north – Van Buren	Northern end of concurrency with SR 161
		459.89	740.12	SR 89 east – Limestone	Northern end of concurrency with SR 89
		461.34	742.45	SR 161	Grade-separated intersection
	Van Buren	481.06	774.19	US 1A – Limestone	Northern terminus of US 1A
	Frenchville	513.06	825.69	SR 162 – St. Agatha
	Fort Kent	524.97	844.86	SR 161 south – Caribou	Southern end of concurrency with SR 161
		525.48	845.68	SR 11 (Pleasant Street)
		525.92	846.39	SR 161 north – Allagash	Northern end of concurrency with SR 161
		526.05	846.60	Route 161 north – Clair	Continuation beyond Fort Kent–Clair Border Crossing on the Clair–Fort Kent Bridge over Saint John River into New Brunswick; northern terminus of US 1
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access        Tolled

• Maine State Route Log via floodgap.com

U.S. Route 1
Previous state: New Hampshire	Maine	Next state: Terminus