Harvey strengthened to a powerful Category 4 hurricane with cities from northern Mexico to Louisiana bracing for flooding, the National Hurricane Center said.
The storm was expected to hit land near Corpus Christi, Texas, around 9 p.m. CDT (0200 GMT) and then dump over 3 feet (90 cm) of rain on the Texas coast and parts of Louisiana as it lingers for days.
The storm was about 35 miles (56 km) off Corpus Christi and packing winds of 130 miles per hour (215 km per hour), the NHC said.
While thousands fled the expected devastating flooding and destruction, many residents defied mandatory evacuation orders and stocked up on food, fuel and sandbags.
"We’re suggesting if people are going to stay here, mark their arm with a Sharpie pen with their name and Social Security number," Rockport Mayor Pro Tem Patrick Rios told reporters Friday, according to media reports.
"We hate to talk about things like that. It's not something we like to do but it’s the reality. People don’t listen."
As many as 5.8 million people were believed to be in the storm's path, as well as the heart of America's oil refining operations. The storm's impact on refineries has already pushed up gasoline prices.
As a Category 4 hurricane on the Saffir-Simpson scale, Harvey could uproot trees, destroy homes and disrupt utilities for days.
If it maintains its intensity, it would be the first major hurricane to hit the mainland United States since Hurricane Wilma struck Florida in 2005. [nL2N1LB1NU]
In Corpus Christi, a city of 320,000 under voluntary evacuation, strengthening winds buffeted the few trucks and cars that continued to circulate on the streets.
The storm toppled wooden roadwork signs and littered the streets with pieces of palm trees as white caps rocked sailboats in their docks.
About 85 miles (137 km) north in Victoria, Mayor Paul Polasek told CNN he estimated that 60 percent to 65 percent of the town’s 65,000 residents defied the mandatory evacuation order.
Jose Rengel, a 47-year-old who works in construction, said he was one of the few people in Jamaica Beach in Galveston that did not heed a voluntary evacuation order.
“All the shops are empty,” he said as the sky turned black and rain fell. “It’s like a tornado went in and swept everything up.”
With the hurricane bearing down on the Texas coast, at least three cruise ships operated by Carnival Corp
Two of them headed New Orleans to pick up fresh supplies, while the third delayed its departure from Cozumel, Mexico. [nL2N1LB219]
The NHC's latest tracking model shows the storm sitting southwest of Houston for more than a day, giving the nation's fourth most populous city a double dose of rain and wind.
"Life-threatening and devastating flooding expected near the coast due to heavy rainfall and storm surge," the NHC said.
President Donald Trump, facing the first large-scale natural disaster of his presidency, on Friday tweeted: "I am closely watching the path and doings of Hurricane Harvey ... BE SAFE!"
Earlier, a White House official said the president was considering a request to issue an emergency declaration, providing federal disaster relief.
Louisiana and Texas declared states of disaster, authorizing the use of state resources to prepare.
The city of Houston warned residents of flooding from close to 20 inches (60 cm) of rain over several days.
Houston Mayor Sylvester Turner advised city residents not to leave en masse, saying "no evacuation orders have been issued for the city."
Chaotic traffic from a rushed evacuation in 2005 with Hurricane Rita proved tragic. "Calm and care!" he said in a tweet.
GASOLINE PRICES SPIKE
Gasoline stations on the south Texas coast were running out of fuel as thousands of residents fled the region. U.S. gasoline prices spiked as the storm shut down 22 percent of Gulf of Mexico oil production, according to the U.S. government.
At a Willis, Texas, station, about 50 miles (77 km) north of Houston, Corey Martinez, 40, was heading to Dallas from his Corpus Christi home.
"It has been pretty stressful. We're just trying to get ahead of the storm," he said.
"We've never been through a hurricane before."
More than 45 percent of the country's refining capacity is along the U.S. Gulf Coast, and nearly a fifth of the nation's crude oil is produced offshore.
Ports from Corpus Christi to Texas City, Texas, were closed to incoming vessels and Royal Dutch Shell Plc
Concern that Harvey could cause shortages in fuel supply drove benchmark gasoline prices
Meanwhile, U.S. gasoline margins
The U.S. government said it would make emergency stockpiles of crude available if needed to plug disruptions. It has regularly used them to dampen the impact of previous storms on energy supplies.
