The Denver Zephyr was a streamlined passenger train operated by the Chicago, Burlington and Quincy Railroad between Chicago, Illinois, and Denver, Colorado. In peak years it ran to Colorado Springs. It operated from 1936 to 1973. The Denver Zephyr continued operating after the Burlington Northern Railroad merger in 1970. BN conveyed the train to Amtrak in 1971; Amtrak merged it with the Denver–Oakland City of San Francisco to form the San Francisco Zephyr and dropped the "Denver" name in 1973.

A streamliner is a vehicle incorporating streamlining in a shape providing reduced air resistance. The term is applied to high-speed railway trainsets of the 1930s to 1950s, and to their successor "bullet trains". Less commonly, the term is applied to fully faired upright and recumbent bicycles. As part of the Streamline Moderne trend, the term was applied to passenger cars, trucks, and other types of light-, medium-, or heavy-duty vehicles, but now vehicle streamlining is so prevalent that it is not an outstanding characteristic. In land speed racing, it is a term applied to the long, slender, custom built, high-speed vehicles with enclosed wheels.