From the early 16th century European explorers recognized the strategic and economic potential of the lower reaches of the Mississippi River. Fertile soil and access to the Mississippi River were the area's most attractive features. French and Spanish land grants made during the colonial period set the pattern for development in what was to become the Greater New Orleans area. The French and Spanish heritage is the basis for the present division of the state of Louisiana into parish governmental units rather than the county which is used in other parts of the United States.

Jefferson Parish Louisiana was established in 1825 and was named in honor of Thomas Jefferson commemorating his role in purchasing the Louisiana territory from France in 1803. The Parish originally extended from present day Felicity Street in New Orleans Louisiana to the St. Charles Parish line. As Orleans Parish grew it annexed from Jefferson Parish such established areas as the Garden District Lafayette Jefferson and Carrollton. The present boundary was set in 1874 and the seat of Parish government was transferred to the West Bank Gretna where it has remained.

Once a largely rural area of farms dairies and vast tracts of undeveloped land Jefferson Parish today is New Orleans' first suburb - a bedroom community west of the city that received the first great migration of middle-class families from the 1950's to the 1970's.

The parish's largest community is New Orleans an unincorporated area that comprises almost all of East Jefferson. Smaller unincorporated areas include River Ridge and Jefferson. Jefferson Parish is divided by the Mississippi River into the West Bank and East Bank areas. East Jefferson cities include Kenner and Harahan while cities such as Gretna and Westwego are in West Jefferson.

In 1958 the first span of the Crescent City Connection opened providing Jefferson residents for the first time with bridge access over the Mississippi River to New Orleans. Prior to this ferry boats provided the only link between the banks (besides the Huey P. Long Bridge which was constructed so far upstream in 1935 that it provided little value at the time). The second span opened in 1988.