The Fairmount branch was part of the New York & New England’s main line from Boston to the Hudson River via Willimantic, Hartford, and Waterbury, CT, later becoming part of the New York, New Haven & Hartford’s Midland Division. Today the Fairmount Line is both a separate line and an alternate routing for some Franklin Line trains (the Franklin Line connects to both the Fairmount Line and the Northeast Corridor at Readville). In the future it may be converted into a new rapid transit line, currently dubbed the Indigo Line.