Some of those now taking shelter from Tropical Storm Harvey at Houston's main convention center may be having flashbacks to a previous storm.

Tens of thousands of people who fled their homes in New Orleans after Hurricane Katrina in 2005 endured squalid conditions at the Superdome football stadium and convention center. Thousands went to Houston, where officials were applauded for sheltering them.

Elected officials in Texas are promising to heed the lessons from Katrina, which left more than 1,800 people dead and caused $151 billion dollars in damage.

Still, the challenges will be huge for Houston. The city of 2.3 million has suffered catastrophic flooding.

Eighty percent of New Orleans was evacuated in 2005. In Houston, residents were told it was safer to stay put. Thousands are now asking to be rescued.