They trot, two by two, in the center of traffic between the skyscrapers of downtown Houston, an anachronism in a constantly changing city. Light rail trains and cars whiz by, while curious onlookers gawk from office windows, cafes and construction sites.

Yet the pairs continue along the street, unbothered by the din and distractions of a modern metropolis, waiting patiently at stoplights and gracious enough to pose for people's camera phones.

They are the horses — and riders — of the Houston Police Department Mounted Patrol, one of the largest such units left in the United States. Far from being relegated to ceremonial functions, the unit performs an important role in urban policing.

“The whole idea behind the mounted unit was to be downtown and to do what we call the Three C's – crime, community and crowds,” said Officer Greg Sokoloski, who has been with the mounted patrol since its founding in 1984.

The mounted patrol, which includes 36 horses and two mules, patrols downtown and Hermann Park daily in addition to working parades, sporting events and other large gatherings, such as protests.

Horses can navigate tight spaces much more easily than police vehicles can, and afford mounted officers a wide field of view.

"In a patrol car, you're kind of isolated; you're inside, you have the windows up and the air conditioning on, Sokoloski said. "People can see us, and we can see you. There's a good feeling, crime-wise, that you're in a safe place when you see an officer on a horse."

While many cash-strapped major cities, such as Boston, have disbanded their mounted patrols, Sokoloski noted that each of the Houston Police Department's horses is donated. The horses must be between 15.2 and 19 hands tall and between two to ten years old, but otherwise can be any breed or sex.

At the department's stables in north Houston, Sokoloski said officers train extensively with their horses to learn the animals' language. He explained officers must earn the trust of their horses so they will not spook in hectic situations.

The specialized unit is open to all officers, regardless of their experience working with horses. The lieutenant of the mounted patrol, Sokoloski explained, first and foremost seeks excellent policemen and women.

"You have to be able to love doing police work," he said. You don't have to know how to ride. We will teach you to do that at our school."

Learning horse language, Sokoloski concedes, is a difficult process. He noted that his horse, Shadow, who stood patiently beside him, "weighs 1,200 pounds, has four legs and thinks completely differently than we do." Through training, Sokoloski taught Shadow to be completely comfortable with people (he tapped his hoof playfully and mugged for the camera during our interview).

Officer Joe Fleming, who lacked riding experience before joining the mounted patrol five years ago, said he was drawn to the prestige of the outfit.

"It's one of the few units in the Houston Police Department that are very sought-after," Fleming said, noting that usually the only way to land an assignment there is if a mounted officer retires or is promoted. In training, Fleming was assigned Molly, a quarter horse and Percheron mix.

"We came up together like two twins, learning to take steps together at the same time," Fleming said, joking that occasionally Molly is of the mind-set that she is a rodeo horse. "She will buck a little bit, but we've pretty much worked that out...I stay on her good side and she doesn't revert back to her old rodeo days."

After our interview at the stables, Fleming and his colleagues led six horses into a trailer, which then drove south on U.S. 59 into downtown. After parking near an underpass in the shadow of Minute Maid Park, the officers saddled up their horses and began riding east, toward Main Street. There, the group would split into pairs to patrol different sections of downtown and Midtown.

As the Houston Press camera crew walked alongside the horses, a man shouted at us through a chain link fence at a construction site.

"What's going on?" he asked. "Some sort of parade?"

No, we explained, they do this every day.