Exploration
For much of its history, systematic exploration of the Everglades was prevented by the dense growth of saw-grass (Cladium jamaicense), a sedge with very sharp saw-toothed leaves. The first European to enter the region was Escalente de Fontenada, a Spanish captive of an Native American chief, who named a lake, Laguno del Espiritu Santo, and some islands, Cayos del Espiritu Santo. Between 1841 and 1856 various United States military forces penetrated the Everglades for the purpose of attacking and driving out the Seminoles, who took refuge here. The most important explorations during the later years of the 19th century were those of Major Archie P. Williams in 1883, James E. Ingraham in 1892, and Hugh L. Willoughby in 1897. The Seminoles were then practically the only inhabitants.

In 1850 under the Arkansas Bill, or Swamp and Overflow Act, practically all of the Everglades, which the state had been urging the federal government to drain and reclaim, were turned over to the state for that purpose, with the provision that all proceeds from such lands be applied to their reclamation. A board of trustees for the Internal Improvement Fund, created in 1855 and having as members ex officio the governor, comptroller, treasurer, attorney-general and commissioner-general, sold and allowed to railway companies much of the grant. Between 1881 and 1896 a private company owning 4,000,000 acres (16,000 km²) of the Everglades attempted to dig a canal from Lake Okeechobee through Lake Hicpochee and along the Caloosahatchee River to the Gulf of Mexico; the canal was closed in 1902 by overflows. Six canals were begun under state control in 1905 from the lake to the Atlantic, the northernmost at Jensen, the southernmost at Ft. Lauderdale; the total cost, estimated at $1,035,000 for the reclamation of 12,500 m², was raised by a drainage tax, not to exceed ten cents per acre ($24.71/km²), levied by the trustees of the Internal Improvement Fund and Board of Drainage commissioners.

The small area reclaimed prior to that year (1905) was found very fertile and particularly adapted to raising sugar cane, oranges and garden vegetables.

Encroachment
The publication in 1947 of Marjory Stoneman Douglas' Everglades: River of Grass was as electrifying an event among naturalists as Rachel Carson's Silent Spring. It drew attention to the vast area that makes South Florida habitable but was being treated by agricultural interests and housing developers as a worthless swamp that the U.S. Army Corps of Engineers would profitably be able to drain. It galvanized President Harry S. Truman's executive order later that year to protect more than 2 million acres (8,000km²) as Everglades National Park.

The strength of Mrs. Douglas' name was such that when legislation designed by lawyers representing the sugar growers' industry proposed to suspend all water quality standards in the Everglades for twelve years, it was named the Marjory Stoneman Douglas Act—until the 103-year old author demanded that her name be removed from the pending bill. It still passed in 1994, renamed the Everglades Forever Act, and was amended in 2000.

The Florida courts had imposed a plan to reduce damaging phosphate levels in the park's waters to below 10 parts per billion by 2006. The phosphate derives from fertilizer used by sugarcane growers. Florida Governor Jeb Bush has now pushed the date back to 2016. Judge William Hoeveler, who was overseeing the cleanup, has been removed following legal action by U.S. Sugar Corporation of Clewiston, Florida.