ETD provides bus service in the municipalities of Chester, Clinton, Durham, Deep River, East Haddam, East Hampton, Essex, Killingworth, Haddam, Lyme, Old Lyme, Old Saybrook, Portland, Westbrook, Middlefield, Middletown, and Madison.

XtraMile microtransit service in the Old Saybrook area began in 2019.

[6] Fixed-route bus services are divided into two divisions: Shoreline (formerly 9 Town Transit) and Middletown (formerly Middletown Area Transit).

[7] RVT operates four microtransit services branded as XtraMile.

[9][10] Media related to Estuary Transit District at Wikimedia Commons