[1] The section from Brunswick, Georgia, to Roscoe, Texas, has been designated by five state legislatures as part of the El Camino East–West Corridor.

The northern terminus of US 84, Pagosa Springs, Colorado, was made famous by C. W. McCall in the 1975 song and album Wolf Creek Pass.

South of Pagosa Springs, the 28 miles (45 km) of the Colorado section of US 84 pass through a portion of San Juan National Forest.

The highway climbs Confar Hill, a drainage divide between the Rio Blanco and Navajo River, before descending into the village of Chromo and passing into New Mexico.

Another 15 miles (24 km) further south, the two return to surface street status, and then travel past downtown Santa Fe via St. Francis Drive.

Along this stretch, US 84 travels parallel to the BNSF Railway, crosses a sandy section called the Muleshoe Dunes, and then passes Littlefield, the birthplace of country singer Waylon Jennings.

US 84 continues in a southeasterly direction through cotton fields and small towns such as Anton and Shallowater, eventually entering Lubbock, the largest city in the South Plains and the birthplace of Buddy Holly.

Signed as Avenue Q, US 84 passes through the heart of downtown Lubbock before making a sharp easterly turn on the southeast side of the city, where it is known as the Slaton Highway.

After bypassing the town of Slaton, US 84 makes another gentle turn to the east, following a generally southeasterly heading through Post, Snyder, and Roscoe, where it merges with I-20.

From this point, US 84 follows I-20, unsigned, until Abilene, where it leaves the Interstate, making a hard southerly turn and forming the western side of a three-quarter loop around the city (along with US 83 and US 277).

From the south side of Abilene, US 84 continues concurrently with US 83 until the two highways split about two miles (3.2 km) northeast of Tuscola, and though still signed as east–west, maintains a due north–south heading.

From McGregor, the highway makes a turn to the northeast to Woodway; this stretch of US 84 is also signed as the George W. Bush Parkway.

After a brief concurrency with State Highway 31 (SH 31) through Bellmead, US 84 continues fairly due east passing through Mexia.

From this point, US 84 continues its easterly path through to rest of eastern Texas, passing through Joaquin before crossing into Louisiana across the Sabine River into the town of Logansport.

It continues east, crossing under I-49, until it reaches Grand Bayou, where it turns to the southeast, merging with Louisiana Highway 1 (LA 1).

After approximately two miles (3.2 km), it turns back again to the east, where it merges with US 71 in Coushatta and stays with that highway until Clarence.

It then travels approximately four miles (6.4 km) to the northeast where it reaches the western terminus of US 98 at Washington, where it is paired with US 98 until Bude and Meadville.

US 84 passes through Enterprise and Daleville which are both very near Fort Novosel which is the United States Army's helicopter training school.

When originally designated in 1926, US 84 was a much shorter route spanning 281 miles (452 km) from Dothan, Alabama, to Brunswick, Georgia.

The major exception was the portion west of Clarence, where SR 6 followed a more southern path from the Texas line through Natchitoches.

[7] The only major realignment since 1934 occurred about 1955 when an improved road was opened between Mansfield and Coushatta that passed through Grand Bayou rather than Evelyn.

[9] Upon its extension, US 84 originally looped southeast on US 45 from Waynesboro to State Line, Mississippi, then east along SR 56 to Wagarville, Alabama, and back to the northeast via US 43 to Grove Hill.