U.S. Route 1 (US 1) in the U.S. state of Connecticut is a major east–west U.S. Route along Long Island Sound. It has been replaced by Interstate 95 (I-95) as a through route, which it closely parallels, and now primarily serves as a local business route. Despite its largely east–west orientation, it is part of a north–south route and is mostly signed north–south.

Most of US 1 through Connecticut encompasses its predecessor, the Boston Post Road, and, in many towns, it is still named Boston Post Road (or Post Road).

This section needs expansion. You can help by adding to it. (May 2008)

US 1 in Connecticut largely parallels I-95 and has many interchanges with it. The route passes through each city and town of Connecticut bordering the Long Island Sound (in addition to the town of Orange).

From Greenwich to Branford, US 1 is mostly a four- or six-lane principal arterial road (with some two-lane sections in dense areas). From Branford to Stonington, US 1 it a two- or four-lane minor arterial road.

US 1 is known as Boston Post Road or Post Road for the majority of its length, but it also encompasses other local street names. The route is known as Putnam Avenue in Greenwich; Tresser Boulevard, West Main Street, and East Main Street in Stamford; Connecticut Avenue in parts of Norwalk; Boston Avenue in parts of Bridgeport; and New London Road in parts of Groton. In Stonington, the route is known as Stonington Road, South Broad Street, and West Broad Street. US 1 is also known as Main Street in Branford and Clinton.

US 1 is concurrent with I-95 in two sections, both of which are river crossings. The western concurrency is between exits 68 and 70 from Old Saybrook to Old Lyme, where the two routes cross the Connecticut River via the Raymond E. Baldwin Bridge. The eastern concurrency is between exits 83 and 85 from New London to Groton, where the routes cross the Thames River via the Gold Star Memorial Bridge.

US 1's two other major bridge crossings closely parallel the I-95 crossings of those rivers. The Washington Bridge over the Housatonic River, connecting Milford and Stratford, as well as the Tomlinson Lift Bridge over the Quinnipiac River in New Haven, are a short distance away from I-95's Moses Wheeler and Pearl Harbor Memorial bridges, respectively.

US 1 also forms a frontage road for I-95 in parts of Fairfield, Stratford, and New London.

This section needs expansion. You can help by adding to it. (May 2008)

US 1 generally follows the old Boston Post Road and turnpike roads built to replace it. Specifically, the Greenwich Road, chartered in 1792, was the part in Greenwich and became part of the longer New York-to-Fairfield Connecticut Turnpike (not to be confused with the contemporary Connecticut Turnpike) in 1806. The New Haven and Milford Turnpike (1802) continued from Milford to New Haven, and the New London and Lyme Turnpike (1807) connected Old Lyme with New London.

Route 51
Location	Old Lyme to East Lyme
Length	9.4 mi (15.1 km)
Existed	1962–1976

US 1 was originally built where it currently exists in Old Lyme and East Lyme. However, from 1949 to 1976, US 1 existed where I-95 currently exists in Old Lyme and East Lyme. From 1962 to 1976, this stretch of road was Route 51, which traveled for 9.4 miles (15.1 km) through Old Lyme and East Lyme and was known as the Boston Post Road. In 1976, US 1 returned to the 9.4-mile (15.1 km) stretch of road, thus eliminating the need for Route 51.

County	Location	mi	km	Destinations	Notes
Byram River		0.00	0.00	US 1 south to NY 120A	Continuation into New York
Fairfield	Riverside	4.83	7.77	I-95 – New Haven, New York City	Exit 5 on I-95
	Stamford	6.93	11.15	Route 137 north (Washington Boulevard) to I-95 / Route 15 (Merritt Parkway) – Transportation Center, UConn	Southern terminus of Route 137; access to I-95 via SSR 493
		8.60– 8.66	13.84– 13.94	I-95 / Route 106 north (Courtland Avenue) – Glenbrook, New Haven, New York City	Southern terminus of Route 106; exit 9 on I-95
	Community of Darien	11.17	17.98	I-95 – New Haven, New York City	Exit 11 on I-95
		11.56	18.60	Route 136 east (Tokeneke Road) to I-95 south – Rowayton, South Norwalk, New York City	Western terminus of Route 136
		11.66	18.76	Route 124 north (Mansfield Avenue) – New Canaan	Southern terminus of Route 124
	Town of Darien	12.51– 12.87	20.13– 20.71	I-95 – New Haven, New York City	Exit 13 on I-95
	Norwalk	14.24	22.92	I-95 – New Haven, New York City	Exit 14 on I-95
		15.69	25.25	Riverside Avenue (SR 809 north)
		15.73	25.31	US 7 to I-95 – New York City, Bridgeport	Exit 1 on US 7
		16.17	26.02	Route 123 north (Main Street) to US 7 north	Southern terminus of Route 123
		16.54	26.62	Route 53 north (East Avenue) to I-95	Southern terminus of Route 53
	Community of Westport	19.22	30.93	Route 33 – Wilton, Saugatuck, Westport Station
		19.83	31.91	Route 136 (Compo Road) – Easton, Saugatuck
	Town of Westport	20.80	33.47	Sherwood Island Connector (SSR 476 south) – Sherwood Island State Park
	Southport	23.31	37.51	I-95 – New York City, New Haven	Exit 19 on I-95
	Fairfield	25.28	40.68	To I-95 south – New York City	Access via Round Hill Road
		25.51	41.05	Route 135 north (North Benson Road)	Southern terminus of Route 135
		25.83	41.57	Route 130 east (Post Road)	Western terminus of Route 130
		26.23– 26.47	42.21– 42.60	I-95 – New Haven, New York City	Exit 23 on I-95
		27.16	43.71	I-95 / Black Rock Turnpike (SR 732 north) – New Haven, New York City	Exit 24 on I-95
		28.15	45.30	Route 58 north – Easton, Redding, Bethel	Southern terminus of Route 58
	Bridgeport	28.68	46.16	Route 59 north – Easton, Upper Stepney	Southern terminus of Route 59
		30.36	48.86	Route 8 south / Route 25 south	Access via Lindley Street; exit 2A on Route 8/Route 25
		30.85	49.65	Route 8 / Route 25	Access via SR 722; exit 2B on Route 8/Route 25
		31.43	50.58	Route 127 (East Main Street) – Trumbull
	Community of Stratford	34.03	54.77	Route 108 north (Nichols Avenue) – Trumbull, Huntington	Southern terminus of Route 108
		34.20	55.04	Route 113 (Main Street) – Paradise Green, Shelton
		34.86	56.10	Route 130 west – Bridgeport	Eastern terminus of Route 130
		34.91– 35.09	56.18– 56.47	I-95 – New York City, New Haven	Exit 33 on I-95
				Route 110 north (East Main Street) – Shelton	Southern terminus of Route 110
	Housatonic River	35.27– 35.43	56.76– 57.02	Washington Bridge
New Haven	Milford	36.31	58.44	I-95 – New Haven, New York City	Exit 34 on I-95
		37.33	60.08	Route 162 east – Downtown Milford	Western terminus of Route 162
		38.91	62.62	To Route 15 (Merritt Parkway / Wilbur Cross Parkway) – New York City, Hartford	Access via Milford Parkway
		39.20	63.09	Route 121 north (North Street) – Orange	Southern terminus of Route 121
		40.01	64.39	I-95 – New Haven, New York City	Exits 39A-B on I-95
	Orange	42.25	67.99	Route 152 north (Orange Center Road) – Orange Center	Southern terminus of Route 152
		43.20	69.52	Route 114 north (Racebrook Road) – Woodbridge	Southern terminus of Route 114
		43.95	70.73	Route 162 west (Bull Hill Lane) – West Haven	Eastern terminus of Route 162
	West Haven	46.06	74.13	Route 122 (Forest Road / Campbell Avenue) – Downtown West Haven, Westville
	New Haven	46.64	75.06	Route 10 (Ella T. Grasso Boulevard) to I-95 – City Point, Hamden
		48.25– 48.81	77.65– 78.55	I-91 to I-95 – Hartford, New London, New York City
		49.23– 49.41	79.23– 79.52	Tomlinson Lift Bridge over the Quinnipiac River
		50.25	80.87	I-95 south / Route 337 east (Townsend Avenue) – New York City, Lighthouse Point Park	Western terminus of Route 337; access to I-95 via SR 741; exit 50 on I-95; to Tweed New Haven Airport
	East Haven	50.65– 51.23	81.51– 82.45	I-95 – New London, New Haven	Exit 51 on I-95
		51.32	82.59	To Route 100	Access via SSR 735
		51.79	83.35	Route 142 east (Hemingway Avenue) – Momauguin	Western terminus of Route 142
		52.06	83.78	Route 100 north (Main Street)	Southern terminus of Route 100
	Branford	53.85	86.66	Route 142 west (Short Beach Road) – Short Beach	Eastern terminus of Route 142
		53.96	86.84	To I-95 south – New York City	Access via SR 794
		54.06	87.00	Route 146 east (Main Street) – Stony Creek	Western terminus of Route 146
		54.81	88.21	To I-95	Access via SR 740
		56.82	91.44	I-95 – New London, New Haven	Exit 55 on I-95
		57.06	91.83	Route 139 north (North Branford Road) – North Branford, Foxon	Southern terminus of Route 139
	Guilford	59.21	95.29	Route 22 west (Notch Hill Road) – Foxon, North Branford	Eastern terminus of Route 22
		61.76	99.39	I-95 – New Haven, New London	Exit 57 on I-95
		63.07	101.50	Route 77 (Church Street) – Guilford, North Guilford
		64.11	103.18	I-95 / Route 146 (Boston Street)	Access via Goose Lane; exit 59 on I-95
		64.35	103.56	Route 146 west (Boston Street) – Guilford Center	Eastern terminus of Route 146
	Madison	67.85	109.19	Route 79 (Durham Road) – North Madison, Durham
Middlesex	Clinton	71.67	115.34	Route 81 (High Street) – Killingworth, Middletown
		72.52	116.71	Route 145 (Old Post Road / Old Westbrook Road) – Winthrop
	Westbrook	76.25	122.71	Route 153 (Essex Road) to I-95 – Essex, Ivoryton
	Old Saybrook	78.19	125.83	Route 166 (Spencer Plain Road) to I-95
		79.52	127.98	Route 154 north (Old Boston Post Road) – Shore Points, Cornfield Point, Knollwood Beach	Southern terminus of Route 154
		80.52	129.58	Route 154 south (Main Street) – Shore Points, Saybrook Point	Southern end of Route 154 concurrency
		80.95	130.28	Route 154 north (Middlesex Turnpike) to I-95 south – Essex, Haddam, New Haven	Northern end of Route 154 concurrency
		81.98	131.93	I-95 north – New London	Southern end of I-95 concurrency; exit 68 on I-95
				Route 9 north – Essex, Hartford	Southern terminus and exits 1A-B on Route 9; exit 69 on I-95
Connecticut River		82.15– 82.63	132.21– 132.98	Raymond E. Baldwin Bridge
New London	Old Lyme	82.86– 83.34	133.35– 134.12	I-95 north / Route 156 south (Shore Road) – New London	Northern end of I-95 concurrency; southern end of Route 156 concurrency; exit 70 on I-95
		83.53	134.43	Route 156 north (Neck Road) – Hamburg	Northern end of Route 156 concurrency
	East Lyme	92.46	148.80	Route 161 (Chesterfield Road / Flanders Road) – Chesterfield, Niantic
		92.97	149.62	I-95 – New Haven, New London	Exit 75 on I-95
	Waterford	97.36	156.69	Route 156 west (Rope Ferry Road) – Flanders, Niantic	Eastern terminus of Route 156
	New London	98.70	158.84	Route 213 south (Ocean Avenue) – Harkness Memorial State Park	Northern terminus of Route 213
		99.99	160.92	Route 85 north (Broad Street) – Waterford, Hartford	Southern terminus of Route 85
		100.89	162.37	Route 32 north – Norwich, New London Waterfront District, State Pier, Hodges Square	US 1 acts as frontage roads for I-95; access to State Pier/Hodges Square via SR 635; access to Waterfront District via Eugene O'Neill Drive
		101.03	162.59	I-95 south – New Haven	Southern end of I-95 concurrency; exit 83 on I-95
	Thames River	101.17– 102.26	162.82– 164.57	Gold Star Memorial Bridge
	Groton	102.21– 102.95	164.49– 165.68	I-95 north / Route 12 north / Route 184 east to Thames Street – Providence, Gales Ferry	Northern end of I-95 concurrency; exits 85-86 on I-95; no southbound access to I-95 north/Thames Street; access to Thames Street via Bridge Street
		103.22	166.12	I-95 north / Route 349 south – Providence	Exit 87 on I-95; exit 3A on Route 349
		105.00	168.98	South Road (SR 649 west)
		105.55	169.87	Route 117 north (Newtown Road) to I-95 – Ledyard	Southern terminus of Route 117
		106.47	171.35	Route 215 east (Groton Long Point Road) – Groton Long Point	Western terminus of Route 215
		108.62	174.81	Allyn Street (SR 614 north)
		108.98	175.39	Route 215 west (Water Street) – Groton Long Point, Noank	Eastern terminus of Route 215
	Mystic River	109.12	175.61	Mystic River Bascule Bridge
	Stonington	109.67	176.50	Route 27 north (Denison Avenue) to I-95 – Old Mystic	Southern terminus of Route 27
		112.48	181.02	US 1A north (North Water Street) – Stonington Borough	Southern terminus of US 1A
		113.63	182.87	US 1A south (Elm Street) – Stonington Borough	Northern terminus of US 1A
		116.78	187.94	Route 234 west (Pequot Trail) to I-95 – Old Mystic	Eastern terminus of Route 234
		117.24	188.68	Route 2 west (Liberty Street) to I-95 – Norwich, Hartford	Eastern terminus of Route 2
		117.37	188.89	US 1 north – Westerly	Continuation into Rhode Island
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access

• US 1 (Greater New York Roads)

U.S. Route 1
Previous state: New York	Connecticut	Next state: Rhode Island