Motor freight services arose quickly with the advent of gasoline and diesel-powered trucks. United Parcel Service had its origins in this era, initially as a private courier service. The general improvement of the highway system following World War II prompted its expansion into a nationwide service, and other similar services arose. At the same time, the contraction of rail passenger service hurt rail-based package shipping; these contractions led to the cancellation of the mail contracts with the railroads, which in turn caused further passenger cuts. Eventually, REA was dissolved in bankruptcy in 1975.[citation needed] Air mail was conceived of early, and scheduled service began in 1918. Scheduled airlines carried high valued and perishable goods from early on. The most important advance, however, came with the "hub and spoke" system pioneered by Federal Express (now known as FedEx) in 1973. With deregulation in 1977, they were able to establish an air-based system capable of delivering small packages—including mail—overnight throughout most of the country. In response, the postal service initiated a comparable Express Mail service. In the same period, they also began contracting with Amtrak to carry mail by rail. Thus at the beginning of the 21st century, the U.S. consumer can choose from a variety of public and private services offering deliveries at various combinations of speed and cost. By 2018, parcel carriers are hauling 14% of U.S. goods, up from 10% 25 years ago, and FedEx’s US domestic volume increased 4.9% in 2018, while UPS reported a 3.3% increase and a 5.6% increase in domestic next-day air package.[7]