I've always thought it interesting that if you blindly follow I-10, you get to go to New Orleans, whether you want to or not. The section of I-12 stays north of Lake Pontchartrain (and Nawlins) completely. I bet they get unplanned visitors all the time.
When I was in the Navy, I visited New Orleans by ship. They took our WWII Aircraft Carrier from the Gulf to the foot of Canal Street for Mardi Gras. We had about 1,000 cots set up in the hangar bay to house all the marching bands that were attending. It took two slow days and a local river pilot to get there from the mouth of the Mississippi. There were times when you could look straight down from the edges of the flight deck and see land - not water. New Orleans is almost 100 miles from the mouth of the Gulf.
It was one heck of a party, though.