west Transportation Airports St. Lucie County International Airport, a general aviation airport. The nearest commercial airports are in Melbourne, Vero Beach, and West Palm Beach. Major highways Interstate 95 U.S. Highway 1 State Road 716 State Road 70 State Road 68 State Road 615 State Road 614 Florida's Turnpike State Road A1A State Road 608 State Road 607 State Road 713 Public bus service St. Lucie County is served by the St. Lucie Transportation Planning Organization (TPO). The TPO is a Metropolitan Planning Organization (MPO), a federally mandated and federally funded transportation policy-making organization responsible for transportation planning, programming, and financing of State and Federal Transportation Funds for St. Lucie County. The TPO is governed by a TPO Board, which is composed of elected officials, representatives from the St. Lucie County School Board, and representatives from Community Transit, a division of The Council on Aging of St. Lucie, Inc. The original bus system started out as a demand response service bus in the 1990s, it only served St. Lucie County. Soon it expanded to a fixed route system, going to predetermined locations along a route. On June 3, 2002, the Florida Department of Transportation (FDOT) approved funding, expanding the bus service to Martin County, and became the Treasure Coast Connector. Passenger trains Until 1968 the Florida East Coast Railway operated Jacksonville to Miami service, with station stops in Fort Pierce and Jensen Beach. Until 1963 long distances passenger trains of the Illinois Central (City of Miami) and Louisville and Nashville (Dixie Flagler and South Wind) from Chicago and Atlantic Coast Line from New York City (East Coast Champion, the Havana Special, and the winter-only Florida Special) made stops in Fort Pierce. The Brightline passenger rail company is extending to the Space Coast and Orlando, north from the West Palm Beach terminus of its West Palm Beach - Miami service. Fort Pierce and nearby Stuart have been jockeying for position as the Treasure Coast station for a return of passenger service, with Stuart edging out ahead. Demographics As of the 2020 United States census, there were 329,226 people, 118,527 households, and 81,648 families residing in the county. As of the census of 2010, there were 277,789 people, 108,523 households, and 74,963 families residing in the county. The population density was 485.7 people per square mile. There were 137,029 housing units at an average density of 239.6 per square mile. The racial