[2] The company is noted for its role in the development of Cape Coral, and pioneering the sales method of installment land purchases.
In the late 1960s, GALC sold 173,000 mi (278,000 km) of swampland, dubbed Golden Gate Estates, to about 40,000 buyers.
The fill resulting from digging flood control canals was used to raise the land level to comply with legal requirements for minimum building elevation.
This involved Rosen's 1957 purchase of 103 sq mi (270 km2) of land located in pristine mangrove swamps for $678,000 and the establishment of offices in strategically important Northeastern and Midwestern towns and cities, where prospective customers were enticed by using high-pressure sales techniques to take a day trip to Southwest Florida to inspect developments and commit to a purchase.
[7] To protect themselves against buyers attempting to wriggle out of the contractual terms of their purchase agreements with GALC following a sudden change of mind and potential defaulters, plots were oversold.
Governor Haydon Burns responded to this criticism by placing Leonard Rosen on Florida's Installment Land Sales Board, which was created to investigate these complaints.
[6] On June 29, 1966, Modern Air became a wholly owned subsidiary of GALC after purchasing the airline's entire participating interest from its previous owner, John Becker, for $807,500 in May-June 1966.
[4] In December 1966, GALC's stockholder meeting resolved to drop "Land" from its name to shorten it to Gulf American Corporation (GAC) to reflect its increasing diversification and approved an employee stock purchase plan worth $600,000.
[5] The court appointed 5 outsiders to monitor Gulf American for a probation period lasting 150 days, a $5,000 fine and required them to issue refunds to buyers who had legitimate grievances.
Another suit came from a Detroit couple who said salesmen misled them about their lot's location, saying it would be 2 1/2 city blocks from the Gulf of Mexico when it was 9 miles (14 km) away.
[5] GAC's dwindling property business in the wake of the recession caused by the 1973 oil crisis resulted in the cancellation of subsidiary Modern Air's contract to fly in prospective land buyers from the Northeast and Midwest to inspect its property developments in various locations in Florida and Arizona at the end of 1973.
These factors combined to reduce residential developments and closure or disposal of non-core activities, including GAC's computer leasing business and Modern Air.