U.S. Route 1 Alternate (US 1A) was established in 1953 when US 1 was rerouted to bypass west of Wake Forest and Youngsville. Predominantly a two-lane highway, with either a median or tree divide in Wake Forest, it follows the old alignment; via Main Street, Youngsville Boulevard, College Street and Park Avenue.
U.S. Route 1 Alternate (US 1A) was established in 1953 when US 1 was rerouted to bypass west Franklinton. A two-lane urban highway, it follows the old alignment through the downtown area, via Main Street.
U.S. Route 1A in Connecticut is a short loop route within the town of Stonington that passes through Stonington borough. US 1 originally went along this route until 1941. US 1A is the only surviving alternate U.S. highway in Connecticut.
The route is 1.93 miles (3.11 km) long and takes the following route: From US 1 to North Water Street, to Trumbull Avenue, to Alpha Avenue, then to Elm St, and back to US 1.
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US 1A should not be confused with Rhode Island Route 1A. In Rhode Island, US 1A exists in segments between Warwick and Pawtucket. Not helping matters is the presence of incorrect signs on both routes, marking Route 1A as US 1A and US 1A as Route 1A.
US 1A runs for 1.7 miles (2.7 km) through Warwick along Post Road and Warwick Avenue. Then in Cranston: it runs for another 1.7 miles (2.7 km) continuing along Warwick Avenue to Norwood Avenue and Narragansett Boulevard before crossing into Providence. There, the highway continues to follow Narragansett Boulevard and turns along Allens Avenue, Eddy Street, Point Street. US 1A is not signed at all in Providence, but in all likelihood, from Point Street, US 1A uses Water Street to enter I-95 EB at Exit 2. Similarly, US 1A SB probably exits I-195 WB at Exit 2 onto Water Street, and turns left onto Point Street. The highway continues on the East Providence Expressway (I-195) into East Providence. US 1A uses another one-way pairing with the eastbound traffic using the expressway, and Warren and Pawtucket Avenues. The opposite direction is routed along Pawtucket (114) and Newport Avenues. The last city through which US 1A runs is Pawtucket where it runs for 2.3 miles (3.7 km) to the Massachusetts state line in Attleboro, traveling concurrently with Route 1A on Newport Avenue to U.S. Route 1.
US 1A was never U.S. Route 1 at any point in time. In Warwick, US 1A used to stay on Post Road east of Route 117 instead of turning north to overlap it. It stayed with Post Road to Pawtuxet Village, then used Broad Street into Cranston to rejoin the current US 1A alignment at Norwood Avenue.
In Portland, Maine's largest city, the original routing of what was US 1A has largely been eliminated but a short section still exists mainly along Portland's waterfront. It now begins at exit 7 on the I-295 freeway (also known as Franklin Street). It travels east along the Franklin Street Arterial until its intersection with Commercial Street and the Maine State Pier. At this point it makes a 90-degree turn onto Commercial Street, which it will follow through the entire waterfront area passing such landmarks as Becky's Diner and the US Customs Service Portland office. It then passes under the four lane ME 77/Casco Bay Bridge roadway, and then continues along Commercial Street (and the waterfront) until its intersection with Valley Street and the Veteran's Memorial Bridge Road. US 1A follows neither routing but instead turns west and north following the Fore River Parkway where it loops back to meet I-295 again at the exit 5 interchange, which also serves Congress Street (ME 22).
US Route 1A in Rockland bypasses the downtown area and begins at the intersection of Camden and Maverick Streets. Traveling westbound along Maverick Street, it passes Rockland Plaza (which is Rockland's second shopping center), and is concurrent with Maine 17 along this section. It then takes a 90 degree turn at a flashing yellow blinker light to turn left (south) onto Birch Street where it meets North Main Street (which was the former alignment of Maine 17) at a traffic light. US 1A then continues along Broadway, passing Oceanside High School as it continues south through the residential heart of Rockland, and encounters additional traffic lights at Rankin and Limerock Streets, until its end at a traffic light at Park Street where it rejoins US 1.
In Milbridge, US 1A provides a more direct route for through travelers, as it branches off from US 1 just north of the main business section of the small town of Milbridge, and is known as Bridge St. It then crosses the Narraguagus River and continues in a northeasterly direction whereas US 1 takes a route that is north/northwest to meet Cherryfield before turning back east while 1A takes the more direct (and southern) route closer to the coast to rejoin its parent just east of Harrington. The length of this segment is 7.8 miles.
Current US 1 alignment. In the early 1950s, a 4-lane divided highway was constructed to relieve congestion in the area. US 1 was assigned to this new highway section with the old road becoming US 1A. The highway section was later incorporated into the Connecticut Turnpike and eventually became I-95. US 1 was re-designated on the old alignment.
Routed along Belden Avenue, Cross Street, and North Avenue. US 1 was originally assigned to West Street, Wall Street, and East Avenue. Since the opening of the US 7 expressway, US 1 was moved to its current alignment along part of this US 1A along Riverside Avenue, Cross Street, and North Avenue. The original US 1 alignment is now town-maintained.
Current US 1 alignment along Kings Highway Cutoff, North Avenue, Boston Avenue, and Barnum Avenue. This US 1A existed until 1963. US 1 originally went along modern Route 130 on Fairfield Avenue, State Street, Stratford Avenue, and Ferry Boulevard connecting the towns of Fairfield and Stratford via downtown Bridgeport.
US 1 originally went along Broad Street, River Street, and Cherry Street. Current US 1 (Boston Post Road) was designated as US 1A. In 1940, the two alignments were swapped. US 1A remained on Broad Street/River Street/Cherry Street until about 1942. Broad Street is now part of Route 162 while River and Cherry Streets are now town-maintained roads.
Routed along Main Street. This was the original alignment of US 1 until the opening of the Saltonstall Parkway in 1941, which was designated as US 1. This US 1A existed until the early 1950s. The eastern end of Main Street is now part of Route 100.
US 1 originally went along Main Street and East Main Street. From 1937 to 1940, current US 1 on North Main Street was designated as US 1A. The routes were swapped around 1940 and US 1A remained on this alignment until 1963. Main Street is now part of Route 146 while East Main Street is a town-maintained road.
US 1 originally went to the town center using Old Boston Post Road then Main Street (now part of Route 154). US 1A was designated on the current US 1 alignment on Boston Post Road. The two routes were swapped around 1940. US 1A on Old Boston Post Road remained until the early 1970s.
Long Hill Road from the I-95 Exit 85 offramp to Poquonnock Road. This was a newly constructed road in 1938 which later became US 1 by 1941. The original US 1 alignment used Thames Street and Poquonnock Road going through the old Borough of Groton (now the City of Groton).