While most people are heading home, others gather for a different purpose -- to catch a glimpse of something hidden in the shadows.
"You can kind of see the awe on their faces when the bats come out en masse," said Suzanne Jurek, a zookeeper at the Houston Zoo and bat specialist.
The bats of the Waugh Street bridge are just getting up. It's a colony of 250,000 and every one of them is a nocturnal hunter.
"They fly for miles and they eat. It's all about the food," Jurek said.
"The most notorious reports of a flying humanoid is that of the Houston Batman," professional cryptozoologist Ken Gerhard said.
This tale takes us to Houston back in the 1950s, when it was a boomtown bursting at the seams.
It was 2:30am on June 18, 1953 in the Houston Heights. Three neighbors claimed they saw something extraordinary just a few feet from their home.
Hours later, the unearthly encounter was front-page news in the Houston Chronicle.
"There's really only one account that I'm aware of and it's a very chilling encounter," Gerhard said. "Subsequently, they were so horrified by their experience that they contacted the local police."
"Hilda Walker, a 23-year-old housewife, and two of her neighbors were sitting on their front porch, and suddenly Hilda noticed a large shadow moving across the lawn," Gerhard said. "It was then that they could make out its form."
One of the witnesses, Howard Phillips, a tool plant inspector, told the Houston Chronicle, "I could hardly believe it, but I saw it."
All three witnesses had a similar description of what they saw that night.
"It appeared to be a very tall man or manlike figure standing about six and a half feet tall but with bat-like wings attached to his back," Gerhard said. "Also seemed to be encased in a halo of glowing light."
We asked graphic designer Michael Charles what he thinks the Batman may have looked like.
"Give it the qualities of the bat -- slender frame, broad shoulders," Charles said. "When you see it, you freeze in your tracks and you just can't move."
And that's all the stunned onlookers said they could do -- just freeze.
"Our automatic response when we're startled or afraid is to freeze up -- the deer-in-headlights effect," said Dr. Peter Norton, an associate professor of psychology and director of the University of Houston Anxiety Disorder Clinic. "We talk about fight or flight as the dominant response. But really it's more fight, flight or freeze."
They said the mysterious figure lingered for 30 seconds or more.
"Then suddenly, the light began to fade out and the figure vanished," Gerhard said.
The details of the Houston Batman may be uniquely 1950s, but the story is not.
"The flying humanoid phenomenon dates back millennia," Gerhard said.
Gerhard, who's finishing a book on the subject, has tracked down similar accounts all over Texas and Mexico. But while sightings are many, the answers remain few.
"What it is we're describing is essentially a biological impossibility," Gerhard said.
"If there were a bat as tall as a man, his wing span would have to be 18 feet or more from wingtip to wingtip. It's not something that you would easily mistake," Jurek said.
We may never know what, if anything, visited the Heights on that night in 1953.
"I'm going to go out on a limb and guess that it probably wasn't a giant winged bat/human creature, but who knows," Norton said.
For now, the Batman creeps deeper into the shadow of legend -- vanished like a colony of bats into the night sky. But remember, just because we can't see them, doesn't mean they're not there.
"It's a great legend. It brings more flavor to the city," Charles said.
We have been unsuccessful finding any trace of the original eyewitnesses to this strange encounter. If you have information about Hilda Walker, Judy Meyer or Howard Phillips, give us a call at 713-669-1313.