The St. Lucie River is a 7-mile-long (11 km) estuary linked to a coastal river system in St. Lucie and Martin counties in the U.S. state of Florida. Its North Fork flows south from St Lucie County into Martin County where it joins the north-flowing South Fork, which was once called the Halpatiokee River, just south of the old Roosevelt Bridge (Old Dixie Highway) in Stuart to form the main St. Lucie River. It then passes under the Florida East Coast Railway drawbridge and the new high-level Roosevelt Bridge (U.S. Route 1) and flows east with Rio on the north side and Stuart on the south until it reaches the northern end of the Sewall's Point peninsula, where it runs south under the Evans Crary Bridge to the end of Sewall's Point, where it flows into the Indian River Lagoon directly west of the St. Lucie Inlet which goes into the Atlantic Ocean.