Auto insurance companies have restricted options for Houston-area drivers looking to purchase new policies and replace cars flooded by Hurricane Harvey, and comprehensive rates are expected to rise after the loss of an estimated half-million vehicles.

Some carriers have imposed temporary limits on selling insurance to customers in Harvey's path, hesitant to assume new risk even as floodwaters recede. Experts expect longer-term changes as carriers reassess their rates after a spate of intense storms across the state.

"Look at our most recent history," said Mark Hanna, spokesman for the Insurance Council of Texas. "This the third flood you've had affecting tens of thousands of vehicles, and that's had a huge impact on comprehensive coverage."

All major carriers ceased extending new coverage immediately before and after the storm, a standard practice within the industry. But some remain reluctant to onboard customers a week and a half after the rainfall at last stopped, citing concerns about continued flooding.

Allstate has maintained a moratorium on new coverage throughout most of Harris County and other storm-affected areas as it processes thousands of claims. Spokesman Roberto DeLeon said the company has lifted such restrictions in some places but hasn't yet determined when it will resume normal business throughout the region.

"We are monitoring the situation day by day," he said. "We take it down to the ZIP code level."

State Farm agents began writing new insurance on Tuesday, but the company hasn't yet resumed online sales. On Friday, it had received about 33,100 claims, up from about 27,500 at the end of last week.

American Access Casualty Company, a small carrier based in Illinois, has slowly resumed sales as it handles a record number of claims. Last year, it processed about 300 in Texas, its largest market, and this year, it expects to receive as many as 2,200.

President Dan Cummings said the company had stopped issuing comprehensive coverage in about 40 counties after the storm and has since resumed sales in about half of them.

"Nobody has seen this before," he said. "The worry I have is this will probably happen more and more frequently in the Houston area because of the population growth."

The Texas Department of Insurance is working to determine the number of carriers that have taken similar approaches after the storm. Spokesman Jerry Hagins said most companies have in the past resumed normal operations within three days after a major storm, but Harvey's magnitude appears to have changed their approach.

"It's still a very fluid situation," he said. "There are some things that aren't typical about the industry response."

Such moratoriums on new coverage have no effect on insured buyers seeking to add a new vehicle to their existing policies after losing one in the storm, and most major dealers in Houston have had little trouble helping customers drive off the lot. But smaller dealers, particularly ones that serve middle- or lower-income customers, have been challenged to find insurers willing to sell policies to customers with minimal or no existing coverage.

Rick Maroney, president of the Houston Independent Automobile Dealers Association, has struggled for days to find insurance for customers at his North Houston dealership on Interstate 45. He said he has never seen such restrictions remain in place for so long after a storm.

"That really hurts a lot of folks out there trying to get a car," he said. "There is a large community of people in Houston who can't really afford the major carriers."

Experts and analysts anticipate the storm, the latest in a series of intense flood and hail disasters throughout Texas, will raise the price of insurance across the board. Already, Texas carriers have raised premiums substantially during the last two years, at times by as much as 20 percent to 30 percent, according to data compiled by Office of Public Insurance Counsel.

Joe Matetich, the agency's deputy public counsel, said the increases account for a wide range of factors, including an overall rise in distracted driving accidents and higher auto repair costs. But he expects the storm will play a role in determining comprehensive coverage rates in affected areas.

"There is a likelihood that the Houston area will see a large increase in the next year or two," he said.

An S&P Global Ratings report noted that large, national carriers with a diversity of products are better equipped to absorb the storm's massive losses than smaller, regional carriers with less capital. But it cautioned that the damages could exacerbate pressure on any company that has already faced higher losses in recent years.

DeLeon said Allstate doesn't anticipate major rate changes as a result of the storm. Like other major carriers, the company budgets for catastrophes and determines its rates based on years-long trends.

"Underwriting guidelines take a longer view of the total environment," he said. "Just because we have one catastrophic event doesn't mean the premiums will increase."

But smaller carriers with less of a cushion might be quicker to raise rates, especially if more disasters sweep the region. Cummings, who has never dealt with a storm of Harvey's magnitude, said he is certain that Houston will soon see higher rates for comprehensive coverage.

"Floods have been occurring annually," he said. "I think it's going to be the new normal."