America's aviation history began on the outskirts of Baltimore on June 24, 1784, with the first lift off of a manned hot air balloon. In the mid 1900s, Glenn L. Martin helped shape that history through development of the first true intercontinental airliner and the production of thousands of World War II war planes at his plant in Middle River. In 1929, the Glenn L. Martin Company built a factory in Middle River, Maryland, and during the thirties the plant was regarded as the most modern in the United States and became famous for manufacturing flying boats known as clipper ships. Martin Air Field, located a half mile northeast of Wilson Point Park, opened in 1942 as the largest privately owned airport in the country. In 1975, it was purchased by the State of Maryland and became Martin State Airport. This aeronautical heritage continues today through the Hubble Space Telescope and other technologies produced by Lockheed Martin, the latest successor to the Glenn L. Martin Company.