Texas State Highway 121

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State Highway 121
SH 121; mainline in red, business routes in blue
Route information
Maintained by TxDOT
Length	85.563 mi[1] (137.700 km)
Existed	by 1939–present
Major junctions
Southwest end	US 67 in Cleburne
Major intersections	I-35W / US 287 / US 377 / Spur 347 in Fort Worth I-820 from Richland Hills to North Richland Hills I-635 in Grapevine I-35E / US 77 in Lewisville Dallas North Tollway in Plano US 75 from McKinney to Melissa US 69 in Trenton US 82 in Bonham
Northeast end	SH 78 in Bonham
Location
Country	United States
State	Texas
Highway system
Highways in Texas Interstate US State Toll Loops Spurs FM/RM Park Rec
← SH 120 → SH 122

State Highway 121 (SH 121) is a state highway angling from southwest to northeast through north central Texas. It runs from Cleburne, Texas at US 67 to SH 78 in Bonham, Texas, just north of a junction with US 82.

Between Fort Worth and Euless, SH 121 is known as Airport Freeway (east of Euless, this name applies to SH 183). East of Coppell, the highway functions as the frontage road for the Sam Rayburn Tollway, a toll road that runs northeast to McKinney. From McKinney to Melissa, the state highway is concurrent with US 75 and the North Central Expressway. Northeast of Melissa, SH 121 is a less-traveled roadway often referred to as the Sam Rayburn Highway.