It was created through the forced consolidation of existing services into a national near-monopoly to ensure the rapid and safe movement of parcels, money, and goods during World War I. REA ceased operations in 1975, unable to adapt to changes in the rail industry, and increased competition from other modes of package delivery.

As railroads developed and expanded through the United States, linking towns of all sizes, stagecoach and horseback gave way to rail.

This service enabled an individual to mail a item larger than a letter, up to 11 pounds (5.0 kg) in weight.

[3][4][5] This was on top of laws, Private Express Statutes, that gave the US Post Office the exclusive right to transport letters.

On December 26, President Woodrow Wilson nationalized the railroads in order to move federal troops, their supplies, and coal.

McAdoo did not view the multiple companies as a favorable arrangement, and pushed for their consolidation into a single organization, which was done on 1 July 1918.

During the war, redundant facilities were eliminated, staff transferred and procedures refined and improved within the new single company.

[5][4] Following the return of railroads to private ownership and operation on 1 March 1920, the task of unwinding American Railway Express needed to be done.

The elimination of redundant facilities and pooling of equipment and personnel had made dismantling it and returning it to its pre-war state effectively impossible.

With few options, the Interstate Commerce Commission granted approval for a monopoly to exist, but encouraged railroads to start their own independent express services.

Share ownership was not required to participate in the Railway Express Agency, with share-less railroads still moving REA traffic.

Federal investment in the interstate highway system after WWII meant that trucks and other vehicles had more flexibility in transporting goods to a variety of cities.

The increase in private ownership of automobiles doomed many passenger lines of the railroads, and industrywide restructuring took place.

Another blow came when the Civil Aeronautics Board terminated REA's exclusive agreement with the airlines for air express.

[1] On 1 June 1970, the company adopted the new name REA Express, Inc., revealing a new image to distance itself from its railroad past and nearly everything that reminded of it.

[12] The effects of the recession literally pulled the rug out from under our carefully planned recovery program and our cash position during the past two months has become critical.

Our attempts to obtain Government‐backed loans and relief legislation have not been successful.From 1969 to the end in 1975, REA Express, Inc. lost an average of $50,000,000 ($415,426,497 in 2023) every year.

[13] In June 1975, wildcat strikes occurred at facilities in New York City, Chicago, St Louis, Kansas City, Philadelphia and Oklahoma in reaction to bankruptcy reorganization efforts during the preceding months, including a 10 percent pay cut, the dismissal of 3,200 employees and closure of 114 terminals.

[7] In 1954, this arrangement remained largely the same, however changes in railroad operations, as passenger rail was gradually vanishing, combined with increased competition from a growing less-than-truckload trucking industry forced revaluation of the agreement in October 1959.

The cars stood out with the simple dark green paint scheme and Railway Express Agency on the side.

[21] Due to REA's connections to the railroads and ICC regulations for most of its existence, packages were required to be transported by rail.

[23][21] American Railway Express would be one of the first air freight companies in the United States, making a test flight on 14 November 1919.