On the morning of March 7, 1949, builder William J. Levitt opened a sales office for a new development of inexpensive single-family homes in a potato field in the center of Long Island's Nassau County. In bitter-cold weather, more than a thousand young couples crowded outside the sales office, waiting for a chance to buy a four-room, 25-by-32-foot house for $6,999--government financed, no money down. Some had camped out in tents for as long as four days.