– Here on Tre­mont Place, there’s a beacon of relief for lunching office workers, tourists on a nearby pedestrian mall and the city’s growing homeless population.

It’s a public restroom. Until last spring it wasn’t easy to find one in downtown Denver.

Encased in a trailer that moves around the city, the three-stall bathroom offers the amenities of any brick-and-mortar facility — lights, running water and flushing toilets. An attendant cleans up between users and polices for illicit activity.

“We’re encouraging people to walk and bike and use transit, and it just makes sense then to offer a public restroom as well in these places where people are gathering,” said Angela Casias, legislative services manager for the Denver Department of Public Works.

Denver is one of several U.S. cities using bathrooms not only to clean up neighborhoods, but also to increase tourism and foot traffic.

Portland, Ore., has become famous for its Portland Loo, a stand-alone steel bathroom stall that sits on a city sidewalk and, unlike a traditional port-a-potty, connects to public water and sewer. San Antonio, San Francisco, Seattle and smaller cities have experimented with similar bathrooms.

City and planning officials say the bathrooms not only clean up streets because they offer a place for people to relieve themselves during big events and for homeless people to use, but that they also encourage those with health conditions to visit downtown areas because they know a restroom will be available.

“Knowing that there’s a restroom there supports you physically and puts your mind at ease,” said Carol McCreary, program manager for Public Hygiene Lets Us Stay Human (PHLUSH), a Pacific Northwest-based advocacy group focused on access to public restrooms. “People will not congregate in multigenerational groups in public space unless the restroom is there.”

Denver has two bathrooms that move around the city. An online map shows where they are and when they’re open.

Public works officials hope to build permanent restrooms at key locations.

Groups like PHLUSH and the American Restroom Association, which advocates for clean restrooms, push policymakers to make restrooms more available and accessible. But getting them to take the issue seriously can be a challenge, McCreary said.

“There will be people who cannot talk about it,” she said. “There will be people who cannot talk about it over lunch.”

Some worry that the restrooms will attract vandalism, crime and drug use.

Denver’s mobile bathrooms have syringe disposal boxes meant for people with diabetes and other conditions. City officials acknowledge that drug users may be shooting up inside. But attendants check on people who are in there too long, and there have been no overdoses, Casias said.

Public comfort stations once populated cities, but as city dwellers turned to the suburbs for housing and shopping, the bathrooms were vandalized and neglected and cities closed the facilities. After the Sept. 11 terrorist attacks, office and apartment buildings stepped up security, limiting access to their facilities.

“People hesitated to go to certain places because there was a fear they wouldn’t find proper sanitation,” said Robert Brubaker of the American Restroom Association.

Some cities have struggled to maintain bathrooms.

After spending $5 million on five self-cleaning restrooms, Seattle sold them for just $12,000 on eBay. The unattended bathrooms became havens for illegal activity and the self-cleaning mechanisms clogged, ultimately costing the city more than it intended to spend on maintenance.