The land that is Orange County was part of the first land to emerge from below the Early Oligocene sea 33.9–28.4 million years ago and is known as Orange Island. Orange County's Rock Spring location is a Pleistocene fossil bearing area and has yielded a vast variety of birds and mammals including giant sloth; mammoth; camel; and the Dire Wolf dating around 1.1 million years ago.
In 1821, there were two counties that formed Florida: Escambia to the west and St. Johns to the east. In 1824, the area to the south of St. Johns County became Mosquito County, and Enterprise was named the county seat. This massive county took up much of central Florida. Mosquito County was renamed Orange County in 1845 when Florida became a state. Several counties, such as Osceola, Seminole, Lake, and Volusia were carved out of Orange County.
Orange County was renamed from Mosquito County for the fruit that constituted the county's main product. At its peak in the early 1970s, some 80,000 acres (320 km²) were planted in citrus in Orange County. A truly impressive sight while driving through the rolling hills of the region were the vast vistas of the dark green foliage of orange trees and the intoxicating scent of the orange blossoms when in bloom. Today, far fewer commercial orange groves remain. The vast majority of groves were destroyed by the devastating freezing temperatures experienced in several severe winters of the early 1980s, followed by the coldest temperatures of the century in the January 1985 cold wave, the worst since 1899.
The financial setbacks, not the first in the history of the grove region, were just too much for many growers and many, economically destroyed, just walked away from the land and its outstanding obligations. Others hung on awaiting any opportunities. One of the major land owners and growers in the region was the Tropicana company. They, however, also threw in the towel rather than try to come back again from these seemingly generational decimations. With no realistic avenues for agricultural utilization of this rural land, and Florida's continuing strong population growth and its attendant needs, (not the least of which was aided and supported by the great success of nearby Walt Disney World and Universal Studios Florida), these areas began and continue to be, swallowed up by growing housing developments. However, several packing facilities and wholesalers are still in Orange County.