Galveston has been dying for decades, long before hurricane Ike. Economic diversity is something that city and county "leaders" don't seem to comprehend the value of - until it is long gone.
Well, about 1/4 of their citizenry died in the space of six hours one Saturday afternoon in 1900. That didn't help.
It's still an anomaly on this list because a) it wasn't really an industrial city or "big" city in 1950 -- third tier city among the country's big towns. And b) Houston had already basically replaced it as a port city before 1950.
The 1900 hurricane and Houston's building the Ship Channel in the 1920's pretty much bypassed Galveston, which was Texas's dominant dockland and entrepot before the 1900 storm. If Galveston's city fathers had built the seawall they'd been talking about since the 1874 Indianola storm, they'd have been okay in 1900, and then who knows where the development would have gone in the 1920's.
The 1900 storm was so bad, that in the 1960's the city's historians were guessing they might have lost as many as 6000 people, as opposed to the first-pass number of 3500 or so worked up by city fathers polling people who'd been involved with body recovery and disposal. By 1999, researchers had upped the toll to over 9,000 with work still continuing but finally winding down. So many people died in the storm, it took 100 years' careful work to figure out just a good, solid guesstimate.