Colorado State Highway 121

State Highway 121
Map of north central Colorado with SH 121 highlighted in red
Route information
Maintained by CDOT
Length:	30.425 mi (48.964 km)
Major junctions
South end:	Waterton Road near Littleton
	US 6 in Lakewood US 40 / I-70 Bus. in Lakewood I-70 / I-76 in Arvada US 36 in Broomfield
North end:	US 287 in Broomfield
Location
Counties:	Jefferson, Denver, Broomfield
Highway system
Colorado State Highways Interstate U.S. State Scenic ← SH 120 SH 125 →

State Highway 121 is a 30.425 mile (48.96 km) long state highway in the U.S. state of Colorado.

The route, also known as Wadsworth Boulevard, Wadsworth Bypass, and Wadsworth Parkway, starts at a junction with Waterton Road in unincorporated Jefferson County (near Littleton and at the entrance to the main plant of Lockheed Martin Space Systems) and ends at the junction of U.S. Route 36, U.S. Route 287, and State Highway 128 in Broomfield at a trumpet interchange. State Highway 121 passes through portions of southwest Denver County.

The name Wadsworth comes from Benjamin Franklin Wadsworth, one of the founders and first postmaster of Arvada. In northwest Arvada, Wadsworth Boulevard passes over Hackberry Hill at the site where a landmark hackberry tree, for which the hill was named, stood before it was cut down to make room for the highway in 1937.