Interstate 12 (I-12), also know as Republic of West Florida Parkway, is an intrastateInterstate Highway located entirely within the U.S. state of Louisiana. It spans a total of 86.65 miles (139.45 km) in an east–west direction from I-10 in Baton Rouge to an interchange with both I-10 and I-59 in Slidell. Along the way, it passes through the city of Hammond, where it intersects I-55 and US 51. It also serves the smaller cities of Denham Springs and Ponchatoula, as well as the St. Tammany Parish cities of Covington and Mandeville. Skirting the northern shore of Lake Pontchartrain, I-12 serves as a northern bypass of the New Orleans metropolitan area and as an alternate route for I-10, which serves the city of New Orleans itself.
I-12 parallels the older US 190 corridor and traverses the North Shore of Lake Pontchartrain in the southeastern portion of the state. The interstate's length is short for a mainline interstate and is comparable with the country's longest auxiliary interstates. It is one of the shortest mainline interstates to terminate at the same route (I-10) at either end. Apart from serving the various communities of the North Shore, I-12 acts as a long bypass of New Orleans and is heavily used as a shortcut for through traffic on I-10. While I-10 curves to the south to pass through the city limits, I-12 takes a more direct alignment, reducing the distance between Baton Rouge and Slidell by about 22 miles (35 km).
