The Hartford and New Haven Railroad (H&NH), chartered in 1833, was the first railroad built in the state of Connecticut and an important direct predecessor of the New York, New Haven and Hartford Railroad. The company was formed to connect the cities of New Haven, Connecticut, and Springfield, Massachusetts. It built northwards from New Haven, opening its first segment in 1838, and reaching Hartford in December 1839. The company reached Springfield in 1844 under the auspices of the Hartford and Springfield Railroad, a subsidiary chartered in Massachusetts. Branches were later built to Suffield, New Britain, and Middletown and operated by the Hartford and New Haven. The H&NH merged with the New York and New Haven Railroad in 1872, forming the New York, New Haven and Hartford Railroad.

The New Haven–Springfield Line is a railroad line owned by Amtrak from New Haven, Connecticut, north to Springfield, Massachusetts, serving the Knowledge Corridor. As a branch of the Northeast Corridor just north of New Haven State Street station, it is served by approximately seven daily Northeast Regional round trips, some continuing from New Haven to Washington, D.C., along the Corridor and others terminating at New Haven as shuttles. On weekends, there is one train daily to Roanoke, Virginia. It is also served by the daily Vermonter, which starts in Washington, D.C., and continues north from Springfield, finally terminating in St. Albans, Vermont. The line is part of the Inland Route connecting Boston and New York via Hartford, Springfield, and Worcester, in contrast to the "Shore Line" along the Connecticut Shore and through Rhode Island.