In 1939 "Union Pacific", a major Hollywood film, was premiered in Omaha to celebrate the city's railroad heritage. The McKeen railroad motor car was a specialized self-propelled passenger car manufactured in Omaha. The railroads continued to be important to freight, business and passenger travel into the 20th century. In 1947 the city's two stations had 114 passenger trains per day that connected all across the West and Midwest. Railroads carried many of the tens of thousands of animals for processing at the packing plants, located near the stockyards and railroads. The city's stockyards and packing industry were the largest in the world by the mid-1950s, surpassing Chicago. Today, the Omaha Rail and Commerce Historic District celebrates this connection, as do the listing of the Burlington Train Station and the Union Station on the National Register of Historic Places. Two large train engines have been placed as monuments and industrial art in Kenefick Park in South Omaha. They face Interstate 80, one of the successor transportation modes. Several major railroads formerly served Omaha, including Chicago, Rock Island and Pacific (CRIP), Chicago, Burlington & Quincy (CBQ); Chicago Great Western (CGW); Illinois Central (IC); Chicago & Northwestern (CNW); Wabash (WAB); Chicago, Milwaukee, St Paul & Pacific (The Milwaukee Road) (CMStP&P); Chicago, St. Paul, Minneapolis and Omaha; Missouri Pacific (MP); and the Union Pacific. Omaha was not spared from the steep decline in passenger service in the second half of the 20th century. Amtrak took over most passenger service in 1971. By the 1980s, it had cut back service to just three trains, all running out of Chicago–the "California Zephyr"to Emeryville, California, near San Francisco; the "Desert Wind" to Los Angeles via Salt Lake City and Las Vegas; and the "Pioneer" to Seattle. The "Desert Wind" and "Pioneer" were eliminated in 1997, leaving Omaha served by only the "California Zephyr." Reflecting the decline in passenger service, Amtrak abandoned the old Burlington station in 1974, and operated from a nearby "Amshack" before moving to a smaller station just 220 feet from the old Burlington station. Omaha is the location of Union Pacific Railroad's corporate headquarters. Located downtown, Union Pacific Center is the largest building by square feet in the state of Nebraska, and the 4th tallest in Omaha.