Connecticut Route 21

Route 21
Map of Windham County in northeastern Connecticut with Route 21 highlighted in red
Route information
Maintained by ConnDOT
Length:	5.67 mi (9.12 km)
Existed:	1944 – present
Major junctions
South end:	Route 12 in Killingly
	US 44 in East Putnam
North end:	Route 193 in Thompson
Location
Counties:	Windham
Highway system
Routes in Connecticut Interstate U.S. State SSR SR ← 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.

Route 21 begins as Thompson Pike at an intersection with Route 12 in northern Killingly and heads north towards the town of Putnam. It crosses into the village of Putnam Heights in the town of Putnam about 0.9 miles (1.4 km) later, becoming known as Liberty Highway. Route 21 runs through the rural areas of Putnam as it heads north towards the town of Thompson. Route 21 intersects with US 44 about 2.6 miles (4.2 km) north of Putnam Heights then enters Thompson after another 0.4 miles (0.64 km). In Thompson, Route 21 becomes known as County Home Road. It passes by the Quinnatisset Country Club, crossing over the Quinnatisset Brook along the way. Route 21 ends a mile later at an intersection with Route 193 in Thompson center. Route 21 is two lanes wide and is classified as a collector road for its entire length. It carries traffic volumes of up to 2,100 per day.