GALVESTON, Texas – Hundreds of thousands of people across the Houston metropolitan area struggled to make their way inland in a vast, bumper-to-bumper exodus Thursday as Hurricane Rita closed in on the nation’s fourth-largest city with winds howling at 150 mph.

Drivers ran out of gas in 14-hour traffic jams or looked in vain for a place to stay as hotels hundreds of miles in from the coast filled up. Others got tired of waiting in traffic, turned around and went home.

An estimated 1.8 million residents in Texas and Louisiana were under orders to evacuate to avoid a deadly repeat of Katrina.

“Whatever happens is going to happen and we are going to have a monumental task ahead of us once the storm passes,” Galveston City Manager Steve LeBlanc said. “Galveston is going to suffer, and we are going to need to get it back in order as soon as possible.”

The storm weakened Thursday from a Category 5 hurricane to a Category 4 as it swirled across the Gulf of Mexico, and forecasters said it could lose more steam before it comes ashore Friday or Saturday.

And in the afternoon, Rita made a sharper-than-expected turn to the right, and it appeared that Houston and nearby Galveston might escape a direct hit. Instead, it looked as if Rita might come ashore near Port Arthur, Texas, or Lake Charles, La., at least 60 miles up the coast.

But it could still be a dangerous storm – one aimed at a section of coastline with the nation’s biggest concentration of oil refineries.

In New Orleans, meanwhile, Rita’s outer bands brought the first measurable rain to the city since Katrina, raising fears that the patched-up levees could give way and cause a new round of flooding.

Highways leading inland out of Houston, a metropolitan area of 4 million people, were clogged up to 100 miles north of the city. Service stations reported running out of gasoline, and police officers carried gas to motorists who ran out. Texas authorities also asked the Pentagon for help in getting gasoline to drivers stuck in traffic, and sent gasoline tankers to take up positions along evacuation routes to help.

To speed the evacuation, Gov. Rick Perry halted all southbound traffic into Houston along Interstate 45 and took the unprecedented step of opening all eight lanes to northbound traffic out of the city for 125 miles. I-45 is the primary evacuation route north from Houston and nearby Galveston.