The Waterbury and Milldale was locally known as the "Green Line" after its green-painted streetcars, which included a pair of unique cars.

[4] The line left Meriden Road near Hitchcock Lake in southern Wolcott and crossed the Meriden–Waterbury Turnpike on a bridge at the top of Southington Mountain.

[7] The first attempt to incorporate the Waterbury and Milldale Tramway was rejected by the state legislature in July 1905.

[7][20] Morris Park, an existing summer resort on Hitchcock Lake, quickly expanded due to traffic brought by the streetcar line.

It required heavier construction than the previous sections, including blasting to remove boulders from the alignment.

For passengers travelling between Waterbury and Meriden, this represented a savings of fifteen minutes, five cents, and one transfer over the previous routing via Cheshire.

[27] As did many streetcar companies, the Waterbury and Milldale sold residential electric power; by 1924, it supplied much of Wolcott.

In September 1927, the Waterbury and Milldale agreed to sell its bus franchise and buses to the competing company.

[35] In October 1933, the Waterbury and Milldale agreed to sell the operating rights to its route to Cooke Street Line, a local bus company.

[43][44] The Connecticut Railway and Lighting Company (CR&L) took over the Cooke Street Line operations on October 1, 1969.

[45][46]: 36  The Northeast Transportation Company in turn over CR&L operations in Waterbury, including the Hitchcock Lake line, in late 1972.

Two additional "semi-convertible" cars (which had windows that could be fully raised on hot days) were acquired from Wason in 1916.

The only double-truck center-entrance Birney cars ever produced, they were originally ordered in 1918 then cancelled by the Cape Breton Electric Company of Nova Scotia.