Los Angeles International Airport (LAX) started out as a municipal airport, known as Mines Field, in 1928. It is now one of the busiest airports, and anchors one of the largest and most important clusters of aerospace technology in the world. In 1936 North American Aviation built a large aircraft plant at the corner of Imperial Highway and Aviation Boulevard, joining those of Douglas Aircraft and Northrop to the south. The plants produced thousands of planes at the airfield during World War II. North American’s buildings have been removed, and the site is now used by commercial air cargo companies. Douglas’s buildings remain, along with many other aerospace companies that continue to operate along the south side of LAX, extending into El Segundo.