Miami has six major causeways that span over Biscayne Bay connecting the western mainland, with the eastern barrier islands along the Atlantic Ocean. The Rickenbacker Causeway is the southernmost causeway and connects Brickell to Virginia Key and Key Biscayne. The Venetian Causeway and MacArthur Causeway connect Downtown with South Beach. The Julia Tuttle Causeway connects Midtown and Miami Beach. The 79th Street Causeway connects the Upper East Side with North Beach. The northernmost causeway, the Broad Causeway, is the smallest of Miami's six causeways, and connects North Miami with Bal Harbour.
What causeway is closest to the south?