Planners made the decision in 1973 to shift I-75's proposed route to cross the Everglades along Alligator Alley over environmental concerns related to upgrading the Tamiami Trail, which runs along the northern border of Everglades National Park. Additionally, they deemed upgrading the Dolphin Expressway to Interstate standards to be highly expensive. By using this route, I-75 would run along the alley to the proposed Port Everglades Expressway, where it would turn south along a new freeway through the western suburbs of Weston and Pembroke Pines to Miami. It was still planned to continue east to I-95, but due to local opposition, I-75 was not built past its current terminus at SR 826 (Palmetto Expressway) in Hialeah. With this new route, the Port Everglades Expressway was then planned to be built as an Interstate highway designated I-595 to provide an Interstate connection between I-75 and I-95.