From the Everglades to the coral reef, South Florida's distinct subtropical environment sets it apart from anywhere else in the United States. The present-day territory of Dade County was established on January 18, 1836, by the Territorial Act of the United States. The area was a hotbed of international competition 400 years ago, with the English and French towards the north and to the south, the Spanish.

The Miami River and Biscayne Bay were the sites of the first colonies. When the U.S. government took control of Florida, the main business was "wrecking," which involved living off the spoils of disasters triggered by sailing too near the coral reefs. To warn passing sailors of the dangerous reefs, the early occupants erected a lighthouse in Key Biscayne in 1825. Later, the advent of Henry Flagler's railroad in 1896 marked the start of the modern age of the county.

Subsequently, thousands of troops were sent to the region for training during World War II. When the war ended, many soldiers returned to live here permanently with their families. In addition, Miami International Airport contributes to the county's status as a North American gateway to Latin America and the Caribbeans.

This county is named in loving memory of Miami and Francis L. Dade (c. 1793-1835), a United States Army Major who fought on what is now known as the Dade Battlefield during the Second Seminole War. Dade was most likely born in King George County, Virginia. As a third lieutenant, he enlisted in the Twelfth Infantry in March 1813 (during the 1812 War). In May 1815, he was assigned to the Fourth Infantry. In 1825 and 1826, he successfully conducted two military missions while in this position. Unfortunately, Dade was slain in what became known as the "Dade Massacre," in a confrontation with Seminole Indians.