The old soda shop in Slidell looks like it hasn’t changed since Elvis was top of the charts. There are banana splits, and jaunty ‘jerk’ hats, hand-frothed sodas, and mini-jukes in every booth. But even this linoleum time-warp, an hour outside New Orleans, isn’t the throwback it seems.

Like the rest of Louisiana’s Northshore region, it had to be rebuilt after Hurricane Katrina. See, it wasn’t just New Orleans that was devastated by the 2005 storm. Towns across America’s Gulf Coast were almost wiped off the map. That’s why, 20 years on, Katrina is still a major topic of conversation here.“My house was completely destroyed by the tidal surge,” sighed the waitress at the nearby Palmettos on the Bayou. “But I’m glad I stayed,” she chirped, swooping in dishes of gumbo and fried green tomatoes to my table. Slidell, she explained, was one of the few places near New Orleans that didn’t lose its railway connection. A lot of chefs also moved to the Northshore after being flooded out of the Big Easy, bringing haute cuisine and farmers’ markets to an area otherwise known for sailing, alligator swamp tours and leisurely bike rides along the Tammany Trace bridleway.

To be known as The Mardi Gras Express, in recognition of the pre-Lent festivities celebrated right across this once French controlled stretch of coast, the twice-daily service will conga its way from New Orleans in Louisiana, to Mobile, Alabama, stopping at fishing villages and Mississippi beach towns where Elvis used to go to escape.

With rail services not due to begin until later summer 2025, and a trip to New Orleans already booked, I’d decided to do the full 150-mile (240km) route by car.

Local friends had told me I’d be mad to go all the way to New Orleans and not explore one of America’s least-explored stretches of coast. They said this sliver combined the coconut sands you find in Florida, with the charm, history and ‘soul food’ unique to the Deep South. It sounded delicious.

Like the train, I had started my four-wheeled adventure in New Orleans, where, within two hours of landing, I’d shunted myself into some seductively-lit jazz bar to hear a five-piece band purr bass-rich melodies.

I’d been keen to head straight into the French Quarter to experience the Big Easy’s famous nightlife. Dropping my bags at the recently opened Copper Vine Wine Pub and Inn, I wolfed down some pan-fried sprouts at its trendy restaurant, and resisted the urge to ‘wash off the flight’ in my enormous free standing bath. That soak would have to wait until the party was over. Not that it ever is. Even if you come outside Mardi Gras, you’ll find the celebrations never stop. Such joie de vivre is baked into the city’s cobbles. During a walking tour of the French Quarter, I came across a star of the local Philharmonic belting out treacly numbers between two parked cars. My guide, historian David Higgins, even played the blues on a shop’s piano as the cashier sang along. The son of one of Fats Domino’s bandmates, Higgins is as Orleanian as louvre shutters and wrought-iron verandahs. He danced and finger-clicked down the street, while transporting us back to times of pirates and slave auctions, streetcars and paddle steamers.

Such Gallic flair isn’t confined to Louisiana. Across the border, in long-Anglicised Mississippi, the locals are pretty wacky, too. Take Bay St Louis, on the soon-to-open railroad line. It had thrown a Dolly Parton-lookalike parade the day I arrived. “She’s never been here,” confirmed Alicein Schwarbecher, who runs the town’s Mockingbird Café. “It’s just a bit of fun.” I’d got chatting to Schwarbecher at breakfast, during which she volunteered the townsfolk’s kayaks for me to go gator-spotting in.

“There are rental companies,” she shrugged. “But you can just ask a local to borrow one of theirs.” I never did test out her theory. But Bay St Louis does seem wildly laid-back. It was practically power-washed from its foundations by Katrina. Not that you’d know today. There’s a chic, Californian feel to the place, with smart shops and eateries carved into the clapboard homes, and live music at its quayside bars.

I stayed opposite the harbour at the Pearl, which, in 2020, became the first hotel to open since the hurricane hit. Built on a formerly vacant lot, the 59-room boutique leans heavily into the region’s maritime heritage, with pictures of trawlers, oysters and crabs on its walls, and splashes of nautical greys and greens in its soft furnishings and bathroom tiles.

See, ‘Fat Tuesday’ may be synonymous with New Orleans, but it actually started in colonial Mobile in 1703. Places like Biloxi and Mobile are more obsessed with Mardi Gras than Louisiana. Sixty per cent of Mobilians, for instance, are members of official parading ‘krewes’. And, as I learned from my guide Cart Blackwell at the Mobile Carnival Museum, its citizens spend tens of millions of dollars each year on all their elaborate floats, crowns and coronation robes. Even my room at the newly opened Admiral Hotel had stuck to the purple and gold Mardi Gras palette, although the lobby had gone full Versailles glam with its marble, gilt, and life-sized oils of French kings.

The region had proved surprisingly varied. There’d been Mississippi beach bars, and New Orleans jazz brunches; grand, white table clothed affairs, and trendy Mobile eateries, like Noble South, serving up LA-worthy ‘farm to-fork’ dishes in the heart of Alabama. It had been a carnival of music and food – only without the crowds. For now...