Gene Hafele, director of the Houston-Galveston National Weather Service office, said about 500,000 people in and around Galveston were in a mandatory evacuation zone, and only about 300,000 left.
Bill Read, director of the National Hurricane Center in Miami, estimated there were about 140,000 people in the smaller, "certain death" zone. About 70 percent of those residents evacuated. That left nearly 40,000 people to contend with the worst of the storm surge.
There is "no one answer" why so many Texas residents ignored the evacuation order, Read said.
Some probably refused to leave because they'd been caught in the chaotic evacuation for Hurricane Rita in 2005, he said.
During that event, roads out of Houston became gridlocked. Officials later estimated that about 90 people died during the 2005 evacuation because of heatstroke, dehydration, and other causes.
Read also said that some of those who refused to leave during Hurricane Ike stayed because they have an intense anti-government attitude. "They think, No one tells me what to do," Read said.
The National Weather Service's Hafele said officials decided to issue the "certain death" evacuation warning because the storm surge from Hurricane Ike would be unlike anything seen on the Texas coast since an unnamed hurricane in 1915.
"People who were living in the storm surge zone had never experienced a surge like this and had no way of knowing how severe this could be," Hafele said