Business US Route 83-S (Bus. US 83-S) is a business loop of US 83 in the Lower Rio Grande Valley region of Texas. The highway serves as the main street for many communities in the area, such as McAllen, Mission, San Juan, Alamo, and more. This is the longest business loop in Texas, traveling almost 47 miles and is the third longest bannered US highway in the state; only US 90 Alternate and US 77 Alternate are longer.

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Bus. US 83-S begins at Interstate 2/US 83 in Harlingen, near the interchange with Interstate 69E/US 77. Leaving the city, the highway serves the town of La Feria, before entering into Mercedes. In the city of Weslaco, the highway passes by the South Texas College - Mid-Valley Campus. Bus. US 83-S next passes through the towns of Donna, Alamo, and San Juan before entering Pharr. In Pharr, the highway intersects US 281, just south of Interstate 69C. Crossing I-2/US 83 for the first time since Harlingen, Bus. US 83-S enters into the city of McAllen. The highway serves as the major east-west road for the city, traveling directly through the city center. In Mission, the highway splits into a one way street, with northbound traffic traveling on Tom Landry Street and southbound on 9th Street. In western Mission, the highway crosses I-2/US 83 again. After the intersection with FM 2062, development along the route begins to drop, traveling mainly through more rural areas of the city. Bus. US 83-S ends at I-2/US 83 on the eastern edge of Peñitas, where I-2 also ends.

The highway was formally signed as Loop 374 until 1991.

State Highway Loop 374
Location	Hidalgo and Cameron counties
Existed	March 20, 1963–January 14, 1991

Texas State Highway Loop 374 is a former state highway loop that was located in Hidalgo and Cameron counties.

Loop 374 was designated in 1963, running from US 83 near the west city limit of Mission, eastward along the old location of US 83 to US 83 near the west city limit of Harlingen. The highway was extended 5.5 miles (8.9 km) west of Mission to US 83 in 1967. Loop 374 was re-routed through Mission in 1987, with westbound traffic being re-routed onto Mayberry Road and Tom Landry Street near the town's central business district. The highway was cancelled and re-designated as Bus. US 83 in 1991.

County	Location	mi	km	Destinations	Notes
Hidalgo	​	0.0	0.0	I-2 east / US 83
	La Joya	2.8	4.5	FM 2221 north
	Peñitas	5.7	9.2	FM 1427 south (Main Street) / Liberty Boulevard
		6.2	10.0	I-2 east / US 83 east	I-2 exit 128
	Palmview	9.0	14.5	FM 492 north (Goodwin Road)
		10.3	16.6	FM 2062 south (Bentsen Palm Drive) – Bentsen-Rio Grande Valley State Park
	Mission	11.8	19.0	I-2 / US 83 / Inspiration Road	I-2 exit 134
		13.3	21.4	SH 107 (Conway Avenue)
		15.8	25.4	FM 494 (Shary Road)
	McAllen	17.3	27.8	FM 2220 (Ware Road)
		18.4	29.6	FM 1926 north (North 23rd Street) Spur 115 south (South 23rd Street) – McAllen International Airport
		19.3	31.1	SH 336 (10th Street) – Airport
		20.4	32.8	FM 2061 north (McColl Road)	West end of FM 2061 overlap
	McAllen–Pharr line	21.0	33.8	I-2 / US 83 FM 3362 north (North Jackson Road) / FM 2061 south (South Jackson Road)	East end of FM 2061 overlap; I-2 exit 144; access to westbound I-2/US 83 via FM 2061
	Pharr	22.2	35.7	US 281 (Cage Boulevard) – Edinburg, Reynosa
	Alamo	26.1	42.0	FM 907 (Alamo Road)
	Donna	28.6	46.0	FM 1423 north (Val Verde Road)	West end of FM 1423 overlap
		29.1	46.8	FM 1423 south (Valley View Road)	East end of FM 1423 overlap
		30.5	49.1	Spur 433 north (Main Street)
		31.2	50.2	FM 493 (Salinas Avenue)
	Weslaco	34.5	55.5	FM 88 (Texas Boulevard)
		36.5	58.7	FM 1015 – Edcouch, Intl Bridge
	​	37.5	60.4	Spur 31 north (Mile 2 West Road)
	Mercedes	39.3	63.2	FM 491 north (Texas Avenue) – La Villa	West end of FM 491 overlap
		40.0	64.4	FM 491 south – Intl Bridge	East end of FM 491 overlap
	​	41.6	66.9	FM 1425 north (Mile 2 East Road)
Cameron	Bixby	42.8	68.9	FM 2556 south	West end of FM 2556 overlap
	​	43.4	69.8	FM 2556 north	East end of FM 2556 overlap
	La Feria	45.0	72.4	FM 506 (Main Street)
		45.6	73.4	FM 733 north (Kansas City Road)
	Harlingen	47.7	76.8	FM 800 (Bass Boulevard)
		51.1	82.2	I-2 west / US 83 to I-69E / US 77 / Spur 54 east	I-2 exit 174
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus