Danielson was the largest cotton manufacturing center in the state. Providence & Danielson cars ran from Danielson through East Killingly into Rhode Island. The Conn. Co. and its predecessors ran north-south through the mill towns along the Quinnebaug River until 1925.

The Peoples Tramway began operating between Wauregan and Central Village in 1902. A branch line went from Central Village to the single street community of Moosup. Trolleys ran through the mill towns along the Quinnebaug River until 1925. South of Central Village trolleys ran on the New Haven RR.

Putnam, located at Cargill Falls on the Quinnebaug River was one of the busiest mill towns in eastern Connecticut. It was served by trolleys until 1925.

Windham was served by cars from Norwich 1903-1936. The mill town of Willimantic, the "Thread City," was also served by cars from Coventry from 1909 to 1926. Both lines ended at the NYNH&H RR but there was no physical connection as the trolleys did not cross the RR tracks.