Due to changes in transportation after the construction of the interstate highway system in the postwar years and shift to trucking, railroads in the late 20th century went through widespread restructuring and reduction. Passenger traffic particularly had declined as more families owned and used private automobiles. Under President Richard Nixon, Amtrak was established to try to continue passenger operations by using existing tracks. It has been subsidized in order to continue service to some areas that had no alternative transportation, as well as to relieve congested roadways in more dense areas, as on the Northeast corridor. Amtrak subsequently bought some tracks from bankrupt railways as well as Conrail.