There were four Railroads, and a Trolley in Monson, only the CV (North-South) & B&A (East-West) still exist and continue in use..

The 4 railroads were the New London Northern, which became the Central Vermont, and later the Canadian National; the second was the Flynt RR; the third was Southern New England Railway, which was part of the Grand Trunk; the fourth is the Boston & Albany which runs South of the County Road. between Wilbraham & Palmer. (on the Assessor map P127-1, it is labeled Penn Central.)

Flynt Quarry had a spur which connected with the N/S line, this was abandoned when the quarry closed in the 1920s.

The original route for the Southern New England (owned by the Grand Trunk) was to go South to North Monson, but was altered to run East through Northern Monson (from the CV tracks, back into Palmer (over the Quaboag) to West Brimfield, and eventually running southeast through Brimfield. In Monson, the original plan crossed the Quaboag somewhere on the State Hospital land. running South on the West side of the valley, before making a U-turn & going North on the East side of the valley & eventually East between Fenton Road the Quaboag river, but neither plan was ever completed, given that the financial backers went down with Titanic.

One point of possible confusion is that the Grand Trunk apparently owned both the Central Vermont & the Southern New England. (From: New London Northern Railroad
In 1896 the Grand Trunk Railway bought the Central Vermont. The Grand Trunk was merged into the Canadian National Railway in 1923.