Roadmaking in Connecticut spans more than 300 years. The amount of detail to cover, even for the third smallest state in the US, won't fit on one page. Instead, I'll give you summaries and highlights, with links to more detailed pages. Note that even general-sounding links (e.g. Interstate Routes) usually limit their coverage to Connecticut.
Though Native Americans maintained trails for perhaps thousands of years, history for us begins with the settling of Europeans in the 17th century.
The first named roads in the state were the Connecticut Path (1633) and Connecticut Bay Path (1635, later called the Upper Post Road). In 1638 the Colony General Court ordered that roads between the new towns of Hartford and Windsor be laid out.
In 1671, the three branches of the Boston Post Road were designated. In 1679, the Court ordered that the existing roads between towns be taken over and renamed the King's Highways. There were about eight of them, and some modern streets named "King's Highway" allude to their existence. Mostly rock- and tree-laden paths, these highways were not fit for a king.
Soon after gaining statehood in 1788, Connecticut started awarding franchises for toll roads. Generally the towns a road passed through were required to buy the land and build bridges; the turnpike corporation would build and maintain the road, and collect tolls.
The first turnpike in the state (and second in the country) was the Mohegan Road linking Norwich and New London in 1792. Eventually, 100 turnpikes were built covering about 1400 miles. Most of them lost money, for lack of capital or competition from redundant routes. By the mid-1800s, most turnpike companies had folded, and the roads reverted to the towns. If a current road is named "____ Turnpike," it probably once charged a toll.
After the turnpike era, towns struggled to maintain roads with scarce funding and little organization. In the 1890s, the League of American Wheelmen, a union of bicycle clubs, led the call for better roads. In 1895, Connecticut joined a growing trend: state highway departments and state road funding.
In 1900, Commissioner James MacDonald pushed for a statewide system of trunk line highways, instead of funding numerous small roads selected by each town. The ten north-south and three east-west roads would cover 1400 miles, roughly the same total mileage as the 100 former turnpikes. During the next 20 years, different lists of trunk lines were proposed as the state sorted out the beginnings of its highway system.
See also: Trunk line system, 1913 proposal
With more roads and more drivers, problems with navigation became apparent. Roads had names, such as the College Highway or Hartford-Norwich Road, and were marked with colored bands on wooden poles. Drivers carried along thick guidebooks with turn-by-turn directions, or early maps notated with key numbers or symbols to associate the dozens of roads with their names.
In 1922, a regional system of route numbering and signing was adopted in New England. These New England Interstate routes were Connecticut's first numbered highways. State route numbers were limited to 100 and above; only the primary New England routes have retained their numbers from that time.
In 1926, the U. S. Interstate route system was designated by the American Association of State Highway Officials (AASHO). Connecticut gained four US routes: US 1, US 5, US 6, and US 7. Two newer routes (US 44 and US 202) were designated in 1935.
As the years passed, Connecticut's numbering convention grew less suitable for increasing motorist use, changing funding, and the route numbering in neighboring states. To fix this, Connecticut renumbered most of its highways on Jan. 1, 1932.
The new 1932 system included a system of unsigned routes numbered above 400. I call them "secret routes", since they're not signposted as numbered highways. Though the numbers are meant for department use only, sometimes they are inadvertently leaked" into the public.
In the 1920s, planners explored ways of relieving traffic on the Post Road, US 1, in Fairfield County. The solution chosen was an inland route, the Merritt Parkway, the first part opening in 1938. The Parkway proved popular, and in 1939 tolls were added to finance an expressway extension to Hartford.
By the time highway construction was halted by World War II, Connecticut had built several sections of expressway or divided highway (US 1 in New London, US 5 in South Windsor, parts of the Wilbur Cross Parkway). After the war, engineers enamored with the expressway's advantages planned extensive networks in Hartford and New Haven. Many twists and turns of Interstates 84 and 91 in Hartford date back to routes chosen in 1945.
In 1944, the beginnings of the modern Interstate Highway System were laid out, although the program didn't get significant funding until 1956. Connecticut's original routes were 84, 91, and 95, all as they are now. In 1956, the additional 1,000 miles nationwide included the proposed Interstate 491 across the Putnam Bridge, and in 1957 I-291 circling Hartford was added. In 1968, Interstates 284 and 484 were added, part of an extensive list of now-cancelled expressways in metro Hartford.
The Connecticut Turnpike, completed in 1958, was designated I-95 from Greenwich to Waterford.
County governments were dissolved in 1960. At the same time, the state undertook a reclassification of its highway system, affecting hundreds of miles of road. Some were transferred between state and town; others were given different numbers. The "secret routes" were almost totally renumbered, creating the district-based system used today. Most of the public renumbering took effect in 1963.
The 1950s and 1960s were golden years for highway planning in the United States, including Connecticut. As the 1970s approached, environmental issues and realization of the ill effects of recently constructed highways brought about "freeway revolts" in some cities and killed many projects in others.
Before then, however, Connecticut expanded its expressway system by leaps and bounds, completing large portions of routes 2, 8, 9, and 52, as well as interstates 84 and 91.
Planning organizations, including the tri-state Regional Planning Association, had grand plans for the state, expanding more than a dozen expressways and creating as many new ones. Imagine these routes as freeways: 68 in Wallingford, 73, 79, 137, or even Route 313. The new highways, proposed to fill gaps in the network or serve future needs, were never built, as the political climate changed and we learned more about construction, traffic, and their effects.
In 1968, the Connecticut and Rhode Island proposal for an interstate highway connecting Hartford and Providence was approved by the FHWA. The proposed highway would be a rerouted Interstate 84; the existing I-84 from Manchester to Sturbridge, Mass. became I-86, as did the proposed I-491 link to Wethersfield. Only two segments of the new I-84 were built, both around 1971, in Manchester and Willimantic.
The year 1973 brought both the Arab oil embargo and a new provision in the Federal Aid Highway act allowing states to use interstate highway funds for other transportation projects, even non-highway. Connecticut traded in funds for I-491 and most of I-291, using the money for the Central Connecticut Expressway and other projects.
Several other planned highways were delayed or cancelled, including the lower half of Route 11 and the US 44 expressway toward Avon.
The economic downturn, lack of federal funding for maintenance (until 1976) and other factors led to the 1983 collapse of the Mianus River Bridge on I-95 in Greenwich. The next year, the state embarked on a 10-year, $5.5 billion infrastructure rehabilitation program.
Since the mid 1980s, the state has built several segments of new freeway, primarily to close short gaps between others. The new interchanges and approaches include I-91 at Route 3, Routes 2 and 3, and I-84 at I-384. Stretches of new road include parts of I-291, Route 8, Route 9, and I-691.
The state also significantly upgraded major sections of interstate highway. Interstate 84 was widened to six lanes from Massachusetts to Vernon, and eight to 12 lanes from there to East Hartford. Interstate 91 was widened to six lanes north of Route 20, and eight lanes from there to Hartford. High-occupancy vehicle (HOV, or "carpool") lanes were added to both I-84 and I-91. A ten-year project to upgrade the 84/91 interchange area, including adding two new ramps, ended in 1998.
The era of highway expansionism is mostly over. The two Indian casinos in the southeast spurred an upgrade to Route 2A, a dust-off of Route 11 completion plans, and talk of a new Route 2A/Route 2 expressway from Route 12 in Ledyard to I-95 in Stonington.
The state is also pursuing upgrades in the Norwalk to Danbury US 7 corridor, as well as Route 25 in Monroe and Newtown. I-84 from Waterbury to Southington will be widened to six lanes, and the same treatment for I-95 from New Haven to New London is under consideration. The latest plans for the Pearl Harbor Bridge (aka Q Bridge) on I-95 in New Haven call for a new 10-lane bridge. A recent study of the West Hartford corridor proposed a busway from New Britain to Hartford, as well as major interchange modifications on I-84 in the area.
Connecticut's newest highways and interchanges are: