10/09/2026
We the trolls under the bridge in Butte La Rose.
FRIDAY LAGNIAPPE ⚜️
Something extra from Louisiana history, culture & life.
WHEN LOUISIANA BUILT I-10 ACROSS THE SWAMP
The remarkable engineering story behind the highway between Baton Rouge, Lafayette & New Orleans
Most states built their Interstate highways across land.
Louisiana had a different problem.
When I-10 pushed west from Baton Rouge in the early 1970s, engineers faced the Atchafalaya Basin — miles of water, cypress swamp and soft ground where building a conventional highway simply wasn’t practical.
Their answer was the Atchafalaya Basin Bridge.
Built from 1971 to 1973, the twin spans stretch roughly 18 miles across the Basin. When they opened in March 1973, they formed the longest Interstate bridge in America.
But the length may not be the most impressive part.
Much of the bridge was precast away from the swamp. Huge concrete components were transported through Louisiana waterways by barge — some traveling about 250 miles — and assembled in the Basin using floating cranes and construction barges.
The project required approximately 174 miles of piling and 170 miles of prestressed concrete girders.
Louisiana even documented the construction in a film with a perfectly appropriate name:
“Swamp Expressway.”
Heading east from Baton Rouge presented another challenge.
Near LaPlace, I-10 had to cross wetlands and the Bonnet Carré Spillway — the massive flood-control system designed to divert Mississippi River water toward Lake Pontchartrain when necessary to protect New Orleans.
Before I-10, travelers heading from Baton Rouge toward New Orleans commonly used Airline Highway — U.S. 61.
Heading west toward Lafayette meant using routes such as U.S. 190 through Krotz Springs, north of the heart of the Atchafalaya Basin.
For generations, Louisiana’s rivers, swamps and floodways determined where travelers could go.
Then engineers figured out how to go over them.
So the next time you’re crossing that seemingly endless stretch of I-10 through the Basin, take another look.
What feels routine today was once one of America’s most ambitious highway-building projects.
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