In the long decades of political hostility between New Orleans and the rest of the state, there was probably a lot of satisfaction that the Crescent City was separated from us by swamps and large bodies of water.

On the other side, New Orleans probably thought that culture and good food died trying to make the swim to Baton Rouge.

No longer.

This year’s spring community read was the New Orleans classic of the late John Kennedy Toole, “A Confederacy of Dunces,” and the Baton Rouge library hosted Lucky Dog vendors for some of its events. Ignatius’ Conradian journey into the heart of darkness — the Greyhound to Baton Rouge — is celebrated for its humor rather than its commentary on the destination.

What’s changed?

Not just the impact of interstate highways and the general mobility of restless Americans, of whom Louisianians are increasingly a part. For Baton Rouge and New Orleans, the impact of Hurricane Katrina can only be described as a watershed moment in terms of the relationship between the two cities.

With the failure of the federal levee system, the flooding of New Orleans and many parts of the surrounding region meant that the short-term exodus of hundreds of thousands of people turned into a long stay, and a great many people lived in the Baton Rouge area for months thereafter.

As Mayor-President Kip Holden recalls it, that was Baton Rouge’s finest hour, and even as most of the attention was rightly focused on the afflicted, the welcome in an hour of need reflected well on the host city, too.

It was a moment of economic epiphany as well. Stephen Moret, then head of the Baton Rouge Area Chamber, stressed that the recovery of New Orleans’ area businesses was critical to the health of the capital region’s economy.

Almost a decade later, the ties that bind the two cities ought to be growing even as growth along the north shore of Lake Pontchartrain extends from Livingston and Tangipahoa toward St. Tammany.

That commonality of interest is reflected in the broad vision of both cities’ leaders, with Holden and Mayor Mitch Landrieu as friendly colleagues. That Baton Rouge has a black mayor and New Orleans a white mayor was probably something that old-timers did not expect, either.

It’s a great idea to pull together community leaders on the “canvass” trips to other cities, as happened recently when a delegation visited Phoenix and Tucson, two cities that also now are growing together. The longtime goal of passenger rail was boosted by that trip because it has been embraced by the Arizona cities; the folly of Gov. Bobby Jindal in spurning federal aid for trains in Louisiana was made more apparent.

Whether it is realistic to combine the aspirational “super-region” of southeastern Louisiana into an official Census Bureau metropolitan area might be a stretch for a while. But the shotgun marriage of almost a decade ago has turned into a more enduring union than the skeptics thought.

Lanny Keller is an editorial writer for The Advocate. His email address is lkeller@theadvocate.com.