Connecticut Route 21

Route 21 marker
Route 21
Map
Map of Windham County in northeastern Connecticut with Route 21 highlighted in red
Route information
Maintained by CTDOT
Length5.67 mi[1] (9.12 km)
Existed1944–present
Major junctions
South end Route 12 in Killingly
Major intersections US 44 in East Putnam
North end Route 193 in Thompson
Location
CountryUnited States
StateConnecticut
CountiesWindham
Highway system
  • Connecticut State Highway System
Route 20 Route 22

Route 21 is a 5.67-mile (9.12 km) state highway in rural northeastern Connecticut. It extends from Route 12 in Killingly to Route 193 in Thompson. It serves as an alternate to Route 12 in the town of Putnam.