About 348,000 people voted early in Bexar County, which represents more than 35 percent of registered voters.
That's lower than record numbers who turned out in 2008, when about 375,000 people voted early.
"Where's that 27,000? Do we think they'll show up tomorrow? Absolutely," Bexar County Elections Administrator Jacque Callanan said.
She expects to see higher numbers on Election Day.
In 2008, 125,000 people voted the day of the election, and she thinks this year it could be more like 140,000.
"We expect to have a lot of questions, (such as), 'Where is my poll site?' 'Where am I voting?'" Callanan said. "Because we did redistricting this year ... please make sure you know what your precinct number is and where you're voting."
For information on where to vote, you can call 210-335-VOTE or go to visit elections.bexar.org.
Polls are open from 7 a.m. until 7 p.m. on Election Day.
"If you're in line at 7 p.m., you will be eligible to vote," Callanan said.