Tri-Rail (reporting mark TRCX) is a commuter rail line linking Miami, Fort Lauderdale and West Palm Beach in Florida, United States. The Tri prefix in the name refers to the three counties served by the railroad: Palm Beach, Broward, and Miami-Dade. Tri-Rail is managed by the South Florida Regional Transportation Authority (SFRTA) along CSX Transportation's former Miami Subdivision, the line now wholly owned by the Florida DOT. The 70.9-mile-long (114.1 km) system has 18 stations along the Southeast Florida coast, and connects directly to Amtrak at numerous stations, and to Metrorail at the Tri-Rail and Metrorail Transfer station and at Miami Intermodal Center.

A second Tri-Rail line on the Florida East Coast Railway corridor, dubbed the "Coastal Link", has been proposed. The line would operate between Toney Penna station in Jupiter and MiamiCentral in Downtown Miami, and add commuter rail service between the downtown areas of cities between West Palm Beach and Miami. Combined with the existing Tri-Rail line, the Tri-Rail system would have a daily passenger ridership of almost 30,000; or approximately 9 million passengers per annum, doubling Tri-Rail's current ridership.