Filing has closed for Louisiana congressional elections. Republicans are running in all six districts. Democrats are only running in the First, Second, and Third Districts. Libertarians are running in all districts except the First District. Independent candidates are running in the First, Fifth, and Sixth Districts. Thanks to Randall Hayes for this information.
There are no congressional primaries in Louisiana. All candidates run in November. Generally the incumbent, or some candidate, gets at least 50% and is elected. But if no one gets 50%, there is a runoff in December. This system was used in Louisiana 1998 through 2006. In 2006, the legislature decided it didn’t like that system, and changed it effective 2008 to a semi-closed primary and an orthodox general election. But then, after a few years, the legislature decided it didn’t like that either, and went back to the old system effective this year.