Homes were built on the north end of Longboat Key in the early 1900's, some of which are still standing.  In the 1920's John Ringling bought hundreds of acres on the south end and planted Australian pine trees along Ringling Boulevard (now Gulf of Mexico Drive) from one end of the island to the other.  He also built the Ritz-Carlton Hotel on New Pass, which was started in 1926 but never finished; it was torn down in 1962 after Arvida bought the land.

During World War II Longboat Key was sparsely inhabited, but near the present Longboat Harbor there was a target range for Army Air Force planes, which roared over firing 50-caliber bullets.  Gates blocked Gulf of Mexico Drive while target practice was held and then opened again to let the few vehicles pass.

The Town of Longboat Key was incorporated on November 14, 1955.  Development started gradually but hit its activity peak in the 1960´s and 1970´s.  Longboat Key Towers was the first condominium built.

Town Commissions gradually tightened the zoning and approved Town water and sewage in the 1970's.  It was estimated at the time that these utilities would serve a population of 26,000.

Since then development has exhausted almost every acre of land, and the zoning has become even stricter.  Today, very few tracts of privately-owned land over a few acres remain undeveloped.