With early voting starting Monday, and more than 800,000 voters expected to cast their ballots during the early voting period in Harris County, top election officials are warning voters to prepare for crowds no matter where and when they cast their ballot in the nation’s second-largest voting entity.

View: Voter Guide: Everything you need to know

The latest voter registration numbers for the Houston area’s top three largest counties show 70.1 percent of voting-age residents in Harris County are registered, a 4 percent jump over the 2012 election.

Fort Bend County now has 89.1 percent of its voting-age residents registered, a 10 percent jump over the 2012 election, while Montgomery County was at 88.1 percent, also a 10 percent jump over 2012.

To handle the big crowds, Harris County Clerk Stan Stanart says the county is opening a record number of early voting sites: 46 polling places, nine more than during the 2012 election, and any voter registered with the county can vote at any of them. Stanart says they’re also keeping those polls open later each night until 6 p.m. during the first week of early voting.

No matter what county you vote in, make sure you bring a photo ID, as required by Texas law. A driver's license, DPS personal ID card, license to carry a handgun, U.S. military ID, U.S. passport, or U.S. citizenship certificate with photo all work.

Anyone who doesn’t have any of those IDs can apply for an Election Identification Certificate for free through DPS.

"Do not wait to the last two days of early voting,” said Stanart. “We will probably do 100,000 people on the last day of early voting."

For more information on polling locations, hours, photo ID, and frequently asked questions, see our comprehensive Voter Guide.