Universal's owners had been wanting to build a theme park on the east coast since the early 1980s. Following rival Disney, Universal chose Central Florida, ironically setting on a site near the intersection of Interstate 4 and Florida's Turnpike that Disney had considered for Walt Disney World 20 years before, but ruled out since it couldn't obtain enough land. Universal was happy with the much smaller site, but construction didn't begin for several years.
Universal's announcement in 1986 that it would begin construction on the park prompted Disney to fast-track plans for its own studio-themed attraction, the Disney-MGM Studios, which opened in 1989.
The park that opened that day looked very different than the one that now stands in the middle of the Universal Orlando Resort. The land that would become Islands of Adventure was USF's parking lot. There was no CityWalk, no hotels, and no parking structures. In fact, some of the land that those would stand upon wasn't even land, as detention ponds lined the edges of the Universal property.