Surrounded by swamps and low-lying delta lands, New Orleans proper (29° 56′ North Latitude; 90° 84′ West Longitude) is an urban oasis lying in a dike-enclosed area between the Mississippi River and Lake Pontchartrain, 107 miles from the mouth of the river. The city and parish boundaries are coterminous, New Orleans being the fourth largest city in land area (365 square miles, of which 166 square miles are water) in the United States. The boundary is very irregular; its total length is 115 miles. On the north lie Lake Pontchartrain and Rigolets Pass; on the east, Lake Borgne and St. Bernard Parish; on the south, St. Bernard, Plaquemines, and Jefferson Parishes; and on the west, Jefferson Parish. The Mississippi forms part of the boundary on the east, south, and west. The greatest distance within the city limits is thirty-four and a half miles from northeast to southwest; the distance between the river and the lake varies between five and eight miles.
Although the built-up section occupies only a small proportion of this large area, the city has expanded to a considerable extent beyond its original limits (the present Vieux Carré). Extension has been made both upstream and downstream and northward to Lake Pontchartrain; a strip of territory (Algiers) on the west bank of the river has also been annexed.
The popular name, 'Crescent City,' is derived from the fact that the site of the original town was on a sharp bend of the river.