Interstate 395 is a lengthy route that leads north from I-95 in southeastern Connecticut to I-90 (Massachusetts Turnpike) and I-290 at Auburn, Massachusetts. The mostly rural freeway follows a portion of the Connecticut Turnpike, extending the former toll road north from I-95 to its eastern spur (unsigned Route 695) to U.S. 6 in the town of Killingly. The remainder of the route in Connecticut replaced Route 52.
As Interstate 395 north ends in Auburn, I-290 east begins. Ramps connect the shared terminus with U.S. 20 (Washington Street) and an access road to the Mass Pike. Coinciding with a sign replacement project along the entire route of I-395 in Connecticut, all exit numbers were renumbered to use a mileage based system in 2015. This was the first freeway in the state to drop sequential based exit numbers.
Planning for the eventual Interstate 395 began as a new route for Massachusetts Route 12 in 1965. Redesignated Route 52 in 1967, work on the freeway began in 1965 at Interstate 90, with completion of the route between Webster southward to the state line by 1968. Building of the road by Eddy Pond however caused problems because of environmental concerns, delaying completion of the freeway in Massachusetts portion to 1977.1
The Governor William O’Neil of Connecticut on August 30, 1982 and Governor Edward King of Massachusetts on October 5, 1982 requested Secretary of Transportation Andrew Lewis, Jr. to grant Interstate designation for Multi State Route 52 between I-95 at the town of Waterford and I-90/290 in the town of Auburn under the provision of 123 U.S.C. 139(a). Both states provided certification that Route 52 met the basic engineering standards for the Interstate system.
The Federal Highway Administration (FHWA) concurred with this assessment and determined that Route 52 was a logical addition to the Interstate System in a letter dated April 18, 1983. The route description in Connecticut was as follows:
I-290 from a junction with FAI Route 95 in East Lyme north to the Massachusetts State line in Thompson.
The assignment of I-290 to MSR 52 was subject to concurrence of the American Association of State Highway and Transportation Officials (AASHTO). Subsequent correspondence with the FHWA and the two states surrounded the choice of Interstate 290 as the designation. The State of Massachusetts indicated
that such a number would be misleading since it indicates a closed loop off I-90 under AASHTO guidelines.
A two digit number was discussed, but FHWA was not receptive at first to one being used:
I-99 may be the only available two digit number which substantially meets AASHTO guidelines, but its use would require renumbering Connecticut 99 which traverses six towns in this state and is of considerable length. Connecticut would not accept this number.
While I-395 would normally describe a spur connecting with I-95, in balance it appears to be the best choice of the available numbers. There are several instances where a 3 digit number beginning with an odd digit is used to designate an interstate routing of considerable length. I-195 in Massachusetts and Rhode Island is one nearby example.
The Connecticut Department of Transportation formally requested the establishment of Interstate 395 for Route 52 to AASHTO in a letter dated May 5, 1983. The applications from Connecticut and Massachusetts were both approved by AASHTO on June 21, 1983. The Massachusetts request further added
The addition of this route as [an] Interstate will eliminate confusion and will facilitate travel movement decisions for the public.