On Friday, I-45 reopened after being flooded in both directions.
Many of the city's streets took on water Thursday. First responders were out in rescue vehicles, checking abandoned cars.
Officers and good Samaritans helped get people to safety. At the freeway, traffic came to a standstill just after lunch and then the water started to rise fast.
"I was going downtown and it was raining, so people are going to drive slow," stranded driver Geoffrey Davis said. "The water's getting high."
At its highest, the water was up to the door handles on SUVs. The water is now starting to recede, but slowly.
More rain is expected Friday.