It spans a total of 85.59 miles (137.74 km) in an east–west direction from I-10 in Baton Rouge to an interchange with both I-10 and I-59 in Slidell. Interstate 12 ( I-12) is an Interstate Highway located entirely within the US state of Louisiana. US 190 between Covington and MandevilleĮast Baton Rouge, Livingston, Tangipahoa, St.
