In the early days of railroads, building a line along the north shore of the Long Island Sound was considered difficult due to the many rivers that fed into it.

On February 16, 1850, a recently-opened continuation of the line to Granby was also leased; further extensions northward into Massachusetts were later acquired by the New Haven and Northampton as well.

When the railroad's first track was built in the 1840s, Hoyt had been a contractor grading portions of it, building bridges, and supplying ties.

On September 7, 1870, the NY&NH and Hartford & New Haven agreed to consolidate into one continuous line from New York to Springfield, Massachusetts.

[2] The line has since passed into Penn Central, Conrail and is now mostly part of Amtrak's Northeast Corridor, with additional passenger service provided by Metro-North Railroad.