The
Upper Post Road was established in 1673 between
New York City and
Boston via New Haven, Hartford,
Springfield, and
Worcester. From New Haven to Hartford, it ran at various times via
Middletown (now roughly
Route 17 and
Route 99) and via
Meriden (now very roughly US 5). North of Hartford, the road remained on the west side of the
Connecticut River, following the general path of present
Route 159. Along this route between New Haven and Hartford, the
Hartford and New Haven Turnpike was chartered in 1798 and opened in 1799, beginning at Grove Street in New Haven and leaving on Whitney Avenue, passing via Meriden and
Berlin, and entering Hartford on Maple Avenue. This was one of the first turnpikes to be built on a straight line rather than along existing roads. In the 1910s, Connecticut and Massachusetts adopted a system of marking major roads by colors. The route from New Haven to Springfield, crossing the Connecticut River at Hartford, was marked with blue bands, signifying a major north–south route. This route crossed the
Quinnipiac River in New Haven, heading north along an old road (now
Route 103 and US 5) to
Tracy, crossing the turnpike and running through downtown Meriden on Old Colony Road, Cook Avenue, and Colony Street. It then used the turnpike alignment from
Lamentation State Park into Hartford. From
East Hartford north to Springfield, another older road was used. When the
New England road marking system was adopted in 1922,
Route 2 was assigned to a route from New Haven north via Hartford and Springfield toward
Sherbrooke, Quebec. This route followed the older blue-banded route from New Haven north to Hartford. At Hartford, Route 2 crossed the Connecticut River on the
Bulkeley Bridge and ran north from East Hartford to Springfield on the east side of the river. US 5 was designated in 1926 along the Route 2 alignment. Between 1926 and 1932, US 5 and Route 2 were cosigned throughout the length of the route. In the
1932 state highway renumbering, the Route 2 designation was removed, leaving only the US 5 designation. Only a small number of changes have been made since then, the most prominent being in the cities of New Haven and Hartford. US 5 initially used Temple Street, Whitney Avenue, Edwards Street, and upper State Street in New Haven, beginning at
US 1 (Chapel Street). By the 1940s, it had been moved onto a bypass of the downtown area, consisting of Edwards Street, Hillside Place, Munson Street, Henry Street, Sherman Avenue, Winthrop Avenue, and Davenport Avenue, ending at US 1 west of downtown. At the time, it still crossed the river on Middletown Avenue; the route leaving to the north on State Street was signed as an alternate route. The main and alternate routes were swapped by the mid-1950s, and US 5 was sent down East Street to US 1. (The alternate is now Route 103.) The old bypass became extensions of
Route 80 and
Route 10 but is now unnumbered. The final changes truncated US 5 to I-91 when I-91 opened in 1966 in New Haven and relocated US 5 to the new
Route 22 connector across I-91 in
North Haven in 1973, leaving the old route on Broadway as unsigned State Road 729. In Hartford, the original alignment of US 5 entered the city on Maple Avenue and made its way to the
Bulkeley Bridge via Main Street, Central Row, and Columbus Boulevard. The opening of the
Charter Oak Bridge and
Hartford Bypass on September 5, 1942 led to US 5 bypassing downtown Hartford on its current alignment;
US 5 Alternate, an alternate route on the west side of the Connecticut River to Springfield, was extended south along Main Street to the beginning of the bypass. In the early 1940s, several sections of US 5 in the Hartford area were upgraded to four-lane boulevards. The Berlin Turnpike segment was reconstructed as a four-lane expressway, with several segments also straightened out. In East Hartford and South Windsor, a new four-lane expressway, John Fitch Boulevard, was also constructed. Both of these roadways opened in 1942. In 1948,
Route 15 was designated on the Berlin Turnpike and Hartford Bypass segments of US 5 in order to connect the
Merritt Parkway and
Wilbur Cross Parkway to the
Wilbur Cross Highway, providing a continuous high-speed route between New York and Massachusetts. ==Special designations==