the mainland of the United States. SR A1A is called 3rd Street in Jacksonville Beach and Neptune Beach. Just south of Atlantic Beach, SR A1A turns inland for several blocks, following Atlantic Boulevard, before resuming a northward course along Mayport Road that ends at the St. Johns River. A ferry takes traffic to the northern section of SR A1A that continues along the coast to just south of Fort Clinch State Park on the estuary of the Saint Mary's River. At that point SR A1A hooks back south to Fernandina Beach and then turns west, going inland 20 miles through Yulee and crossing I-95 and U.S. Highway 17. It ends at U.S. Highway 1, U.S. Highway 23, and U.S. Highway 301 in Callahan. This section west of Fernandina Beach, is also marked as SR 200, but SR A1A signs are displayed at every cluster of signs, though a designated direction is only above the SR 200 signs. History Pre-1945 alignment Prior to the 1945 renumbering, the route that became SR 1 had the following numbers: Initial alignment SR 1 was defined in the 1945 renumbering as: Alignment modifications Since then, the following changes have been made: Jungle Trail The Jungle Trail (pre-1945 State Road 252) was part of A1A in northeastern Indian River County, Florida. The narrow, road is located between Old Winter Beach Road and the current A1A, along the western side of Orchid Island, and is unpaved. It is part of the Indian River Lagoon Scenic Highway system, and the southernmost road in the highway system. Part of the trail goes through the Pelican Island National Wildlife Refuge. The road started as a means to quickly transport citrus to packinghouses on the mainland, then in the 1930s and 1940s became more used by tourists. On August 1, 2003, it was added to the United States National Register of Historic Places. Major intersections County Road A1A County Road A1A is a county road in four counties in the U.S. state of Florida. The route is discontinuous and functions as a spur of State Road A1A. Palm Beach County CR A1A in Palm Beach County is a former routing of SR A1A through Juno Beach and Jupiter. It serves as a paralleling alternate route to Federal Highway (US 1), and is often erroneously signed as SR A1A despite its official county designation and maintenance. Martin County The longest of the