The meridian 78° west of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, North America, the Atlantic Ocean, the Caribbean Sea, Central America, South America, the Pacific Ocean, the Southern Ocean, and Antarctica to the South Pole.
The 78th meridian west forms a great circle with the 102nd meridian east.
Starting at the North Pole and heading south to the South Pole, the 78th meridian west passes through: