Taking a cue from the suffering in New Orleans, officials called for a voluntary evacuation of this island city as Hurricane Rita (search) threatened to blow across the Gulf of Mexico and slam into the Texas coast by this weekend.

This month marks the 105th anniversary of the hurricane that wiped out Galveston in one of the deadliest natural disasters in U.S. history. An estimated 8,000 people were killed.

Gov. Rick Perry (search) recalled all emergency personnel helping with recovery from Hurricane Katrina (search) to prepare for Rita, including almost 1,200 Texas National Guard members.

• Click here to track Hurricane Rita.

"Obviously it's heightened because of Katrina," Galveston County Judge Jim Yarbrough said. "Nobody wants to make a mistake."

Rita, approaching the Florida Keys, was upgraded to a hurricane Tuesday morning when sustained wind reached 75 mph.

"The time is now to begin mobilizing our resources and implementing our plan to ensure an orderly response before Texas is hit," Perry said.

Texas already is host to Hurricane Katrina evacuees from New Orleans, especially in the Houston area, and Arkansas Gov. Mike Huckabee (search) said emergency officials told him to be prepared to take them in because of Rita.

"We could potentially be looking at taking an enormous amount of people from Houston," Huckabee said. "We're going to have to prepare in the event. It would tax us if we had to, but we would do it."

Arkansas already is home to about 50,000 Katrina evacuees, most of them staying with friends and relatives.

Various computer projections of Rita's course suggest it could be in the northwest Gulf of Mexico near Mexico or Texas by the weekend, after crossing the gulf's warm water that supplies energy to tropical storms.

Officials in Galveston, which is some 40 miles southeast of Houston, said residents should begin leaving Tuesday.

"Today is boarding up and decision day for Galvestonians," city spokeswoman Mary Jo Naschke said Tuesday morning.

Buses were to begin running Wednesday morning for people who can't leave on their own, taking them to shelters about 100 miles north in Huntsville. About 250 people had already made reservations for the bus as of noon Monday, Naschke said.

Residents may take their pets along on the buses if the animals are in cages, Mayor Lyda Ann Thomas (search) said.

"We found that so many people didn't want to leave New Orleans because they didn't want to leave their pets behind," she said.

Officials said a mandatory evacuation could be ordered if Rita strengthens into a Category 3 hurricane, with wind of up to 130 mph and the potential to create flooding up to 8 miles inland.

The approaching storm was affecting offshore oil operations, already hobbled by Katrina damage. Chevron Corp., Shell Oil and BP PLC all began evacuating employees from oil and gas platforms. Marathon Oil Corp. was evacuating 40 people doing repair work on three platforms damaged by Katrina, a spokesman said Monday.