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.

The Northeast Regional is an intercity rail service operated by Amtrak in the Northeastern and Mid-Atlantic United States. In the past it has been known as the NortheastDirect, Acela Regional, or Regional. It is Amtrak's busiest route, carrying 9,163,082 passengers in fiscal year (FY) 2023. The Northeast Regional service received more than $787.7 million in gross ticket revenue in FY 2023.