In Louisiana, an 18.2-mile (29.3 km) stretch of elevated highway between Lafayette and Baton Rouge is known as the Atchafalaya Swamp Freeway, as it goes over the Atchafalaya River and the adjacent swamps and crosses the Mississippi River at the Horace Wilkinson Bridge. In Baton Rouge, Interstate 12 splits off to head north of Lake Pontchartrain and bypass Interstate 10's long southward jog through New Orleans and reconnects with Interstate 10 at Slidell. In New Orleans, a stretch of I-10 from the I-10/I-610 split near the Orleans-Jefferson parish line to the U.S. Route 90 / U.S. Route 90 Business interchange is known as the Pontchartrain Expressway. A dip near the 10-610 interchange to go underneath a railroad track is one of the lowest points in New Orleans, and is highly susceptible to flooding. Pictures of water dozens of feet deep during Hurricane Katrina are commonplace. Near Slidell, the final stretch of I-10 through the Mississippi state line is known as the "Stephen Ambrose Memorial Highway".
I-310 and I-510 are parts of what was slated to be I-410 and act as a southern bypass of New Orleans. I-610 is a shortcut from the eastern to western portion of New Orleans avoiding the I-10's detour into New Orleans' Central Business District.