The Hartford Line is a commuter rail service between New Haven, Connecticut, and Springfield, Massachusetts, using the Amtrak-owned New Haven–Springfield Line. The project is a joint venture between the states of Connecticut and Massachusetts, with support from the federal government as well. CT Rail-branded trains provide service along the corridor, and riders can use Hartford Line tickets to travel on board most Amtrak trains along the corridor at the same prices. The service launched on June 16, 2018.

New Haven is a city in New Haven County, Connecticut, United States. It is located on New Haven Harbor on the northern shore of Long Island Sound and is part of the New York City metropolitan area. With a population of 135,081 as determined by the 2020 U.S. census, New Haven is the third largest city in Connecticut after Bridgeport and Stamford, the largest city in the South Central Connecticut Planning Region, and the principal municipality of Greater New Haven, which had a total population of 864,835 in 2020. Prior to 1960, it was the county seat of New Haven County until the county governments were abolished that year.