A total of seven special routes of U.S. Route 377 currently exist, all of which are located in the state of Texas.

U.S. Route 377 Business J (Bus. US 377 J) is a business loop of US 377 serving the town of Stephenville, Texas in Erath County. The highway is known locally as Washington Street and briefly passes through the main campus of Tarleton State University.

The route was originally designated in 1960 as Texas State Highway Loop 195 (Loop 195), running from US 67 / US 377 west of Stephenville to US 281 near Stephenville Clark Regional Airport. Loop 195 was extended to US 377 northeast of Stephenville in 1962, forming what is now known locally as the South Loop. In 1965, Loop 195 swapped routes with US 377, with Loop 195 running through town along Washington Street while US 377 was re-routed onto the South Loop. Loop 195 was cancelled in 1990 as the highway was re-designated to Bus. US 377 J.^[2][1]

The entire route is in Erath County.

Location	mi[3]	km	Destinations	Notes
Stephenville	0.0	0.0	US 67 south / US 377 south	No access to northbound US 67 / US 377
	1.9	3.1	SH 108 (Graham Street)	Access to Texas Health Harris Methodist Hospital Stephenville
	2.7	4.3	US 281
​	4.3	6.9	US 377
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Incomplete access