The Jefferson Highway was an automobile highway stretching through the central United States from New Orleans, Louisiana, to Winnipeg, Manitoba in Canada. The Jefferson Highway was replaced with the new numbered US Highway system in the late 1920s. Portions of the highway are still named Jefferson Highway, for example: the portions that run through Jefferson Parish, Louisiana; East Baton Rouge Parish, Louisiana; Lee's Summit, Missouri; Osseo, Minnesota; and Wadena, Minnesota.

Jefferson Parish is a parish in the U.S. state of Louisiana. As of the 2020 census, the population was 440,781. Its parish seat is Gretna, its largest community is Metairie, and its largest incorporated city is Kenner. Jefferson Parish is included in the Greater New Orleans area.