Established as one of the original highways of 1926, it originally ran only to Holbrook, Arizona, then was extended in 1934 as a coast to coast route, with the current eastern terminus near the Atlantic Ocean in Atlantic, North Carolina, and the former western terminus near the Pacific Ocean in Los Angeles, California.

Before the completion of the Interstate system, U.S. Highway 70 was sometimes referred to as the "Broadway of America", due to its status as one of the main east–west thoroughfares in the nation.

US 70 was later re-routed again west of Alamogordo, New Mexico along its current route to Globe, as well as being concurrent with US 60 to a common terminus in Los Angeles, California.

U.S. 70 then crosses Interstate 25, and has been upgraded at this point to a controlled access highway until entering the foothills of the Organ Mountains.

After splitting off to the northeast, U.S. 70 begins an ascent into the Sacramento Mountains and enters the Lincoln National Forest.

The road then runs across the Mescalero Apache Indian Reservation and near the resort town of Ruidoso.

[11] U.S. 70 then becomes a four-lane divided highway near Wilson and runs through Lone Grove before entering the city of Ardmore, where it briefly heads south on Interstate 35, bypassing the central business district.

The two routes then approach Hugo, where they serve as the southern terminus of the Indian Nation Turnpike.

It then meets U.S. 259 and State Highway 3 northeast of town and overlaps them into Broken Bow, forming a wrong-way concurrency with SH-3.

U.S. 70 enters Arkansas eight miles[12] (13 km) west of De Queen, and crosses through the north part of the town where it meets the combined U.S. 71/U.S.

The two highways run concurrently to the state capital, Little Rock, where U.S. 70 splits off from I-30 at Interstate 430 at Exit 129.

The two routes remain close through West Memphis, Arkansas, where U.S. 70 runs along Broadway Blvd.

[16] Past the Memphis city limits in the suburb of Bartlett, U.S. 64 separates from U.S. 70/79, taking a more southerly routing through the state.

U.S. 70, now concurrent with only its unsigned designation of State Route 1, heads east, interchanging with I-40 at exit 66 before entering Jackson.

At Huntingdon, U.S. 70 Alternate rejoins US 70 as the main route turns to the east toward New Johnsonville, where it crosses the Tennessee River.

U.S. 70 progresses eastward, roughly paralleling the Cumberland River to an interchange with State Route 155 east of downtown.

From Crossville eastward to the North Carolina state line, U.S. 70 closely parallels I-40, passing through the Roane County cities of Rockwood and Kingston.

From there, it goes southeast to Salisbury, where it starts to parallel I-85 north through Lexington, Thomasville, High Point and Greensboro, in concurrency with I-85 Bus/US 29.

Entering Alamance County, it expands to a four-lane expressway through the city of Burlington, then returns to 2 lanes through Mebane, Efland and Hillsborough.

After a brief overlap with I-40 near Garner, it continues in a southeasterly direction, briefly concurrent with Interstate 42, as it goes through or bypasses the cities of Clayton, Smithfield, Selma, Goldsboro and Kinston.

After passing through Morehead City and Beaufort, it drops back to a two-lane rural road as it travels close along the Core Sound.

After passing the southern terminus of NC 12 (which connects to the Outer Banks), near Sealevel, US 70 ends its seven state tour in the community of Atlantic.

During the earliest days of the automobile, and earlier, American highways were disorganized affairs of widely varying quality.

A companion effort was launched to create a transcontinental highway stretching across the southern half of the country, this one named in honor of Confederate States of America general Robert E. Lee.

[19][20] That same year, the eastern terminus of US 70 was extended to Atlantic, North Carolina, where it remains to this day (albeit in a slightly different location).

A year later, US 70 was extended along Valley Boulevard and reached downtown Los Angeles at U.S. Route 101 running concurrent with US 99 and/or US 60 throughout its course west of Globe.

After being removed from California, US 70 ended at the California/Arizona state line in Ehrenberg until 1969, when it was further truncated to its current endpoint in Globe.

[23] Robert Mitchum and Don Raye's song, "The Ballad of Thunder Road" immortalized in the 1958 film of the same name, follows a family of anarchistic moonshiners who engage in run-ins with the police.

About 4 miles (6.4 km) long, it runs mostly parallel to, and just north of, the present alignment, jogging a bit farther around the AR 15 junction.

Furthermore, US-70 does not "disappear" at these splits; thus, these two highways both co-exist with the main route and serve as additional branches.