The environment of Florida in the United States yields an array of land and marine life in a mild subtropical climate. This environment has drawn millions of people to settle in the once rural state over the last hundred years. Florida's population increases by about 1,000 residents each day. Land development and water use have transformed the state, primarily through drainage and infill of the wetlands that once covered most of the peninsula. Much of Florida consists of karst limestone veined with water-filled caves and sinkholes, which provide homes to many species of aquatic life, some unique to particular Florida locations. As urban and suburban development have increased over the last decades, demand for groundwater has also risen, resulting in damage and drying out of portions of the cave system. This has led to ground subsidence as dry caves collapse, threatening property as well as ecosystems. Restoration of the Everglades has long been recognized as an environmental priority in the state. In 2000, Congress passed the Comprehensive Everglades Restoration Plan, a $7.8 billion, 30-year project aimed at preservation and restoration of the region and its unique combination of environments. By 2018, 30% of the land area of the state was in conservation. History Population growth and development The 1900 United States Census identified only four cities in the state of Florida with more than 5,000 inhabitants: Jacksonville, Pensacola, Key West, and Tampa. The total population of the state was recorded as 528,542. The southern third of the state was sparsely populated, and much of it was partially submerged marshlands. A few attempts at diverting the flow of water from Lake Okeechobee to the land to the south had occurred as early as the 1880s, but it was not until the election of Governor Napoleon B. Broward in 1904 that any significant drainage occurred. Broward had campaigned on a platform that included draining the Everglades and selling off the resulting land. Beginning in 1906, and continuing until 1913, over of canals were dug, creating the Miami Canal, the North New River Canal, and the South New River Canal. An even more ambitious and expansive program followed, resulting in the construction of six large drainage canals and numerous smaller canals, totaling ; of levees; and 16 locks and dams over a 14-year period, from 1913-1927. As land was reclaimed from the Everglades, farmers moved in. Vast farming areas sprang up in southeastern