Upgraded interchange at I-91 includes a direct connector over Route 75 to Day Hill Road.

Route 75 has four lanes at the I-91 interchange and north of Route 20 into Suffield.

The original highway through Windsor, Poquonock and Suffield was created in the early 1920s. State Highway 110 ran along parts of today's routes 159 and 75. Starting in Hartford, it followed Main Street north to Windsor Center; Poquonock Avenue into Windsor Locks and Suffield; and then Mapleton Avenue, northeast and then north across the state line.

When state roads were renumbered in 1932, SH 110 was split up among US 5A (today's Route 159), and Route 75, which included today's route from Windsor to Suffield, and the Mapleton Avenue route back to US 5A. Route 75 began and ended at US 5A.

In 1950, Route 75 was relocated from Mapleton Avenue to North Street, and extended into Massachusetts.

The state was proposing a new connector between Route 75 and Route 159 in Suffield to reduce traffic congestion in town. The bypass would start about half a mile south of the intersection of Austin Street and Route 75 (Main St) and join Route 159 (East St) about 1/5 mile south of Boston Neck Road. (Hartford Courant, 10/8/95)

In January 2001, a segment from Austin Street in Suffield to the Massachusetts border was submitted to the Connecticut Scenic Road Advisory Committee. In March 2001, the committee determined that Route 75 near Austin Street did not meet the criteria, but approved the segment north of Stony Bridge Brook.

For fun: extend eastward over new Connecticut River bridge to US 5/Route 194 in East Windsor; follow 194 south to Route 30; follow Buckland Street, Adams Street, and Keeney Street through Manchester to Route 94 in Glastonbury.

• "Route 75 in Suffield being considered as scenic road.", Press Release, ConnDOT, Jan. 22, 2001.
• "Section of Route 75 in Suffield designated as scenic road.", Press Release, ConnDOT, Mar. 23, 2001.
• "MikeD31784". "Route 75." Personal email, Mar. 30, 2002.

No longer assigned. Old route number for North Street in Windsor Locks, which parallels modern-day Route 140 between routes 75 and 159. Created in 1935; deleted in 1949.

13.85 miles; from Route 17 in Durham to Route 146 in Guilford.

Commissioned in 1932, from part of the old Route 112.

Route 77 is a designated scenic road. The Danbury News-Times writes:

In July 1998, a coalition of seven local groups (called the Group of Seven) called for another public hearing, saying they didn't hear about the October meetings. The DOT says the project is too far into the design phase for another public hearing, but an informational meeting will be held.

Route 78 has its own page.

14.48 miles; from Route 17 in Durham to US 1 in Madison.

Commissioned in 1932; few changes since then... except on paper. In the late 1960s, the Tri-State Transportation commission included a Route 79 freeway in its interim highway proposals. The freeway would have paralleled Route 79 to the east leaving Durham, and connected with the Hammonasset Connector (SR 450) in Madison.

Old Route 79, Madison

Durham Road in Madison is now a straight shot between Woodland Road and Bradley Road, including a bridge over the railroad tracks. In the 1940s, however, (and possibly earlier and later), there was no crossing, and Durham Road was cut in two. Going north from US 1, Route 79 diverged to the east, following Bradley Road and another street over the tracks to reconnect with Durham Road.

At some point a Durham Road bridge was built, and the "other street" mentioned above, whatever it was called then, is now called Old Route 79.

Scenic Road status proposed in 2003

In February 2003, Madison officials announced their intent to have US 1 in town designated a state scenic road. They said they would follow this up with an application for part of Route 80; and also for Route 79.

• "Madison trumpets Route 1 scenic status." Hartford Courant, Feb. 13, 2003.