Washington, DC CNN Business  — 

Uber just took one more step toward becoming a one-stop shop for all our transportation needs.

Uber users in Las Vegas can now buy bus tickets using the app. Customers can compare public transportation prices and arrival times with Uber’s service, and then pay for whichever option they prefer, the company announced at this week’s Consumer Electronics Show. The service will gradually roll out to users in the coming weeks.

Las Vegas is the second city in which Uber (UBER) is offering the service. Uber (UBER) started selling public transit tickets in Denver last May.

The offering adds an interesting twist to the complicated relationship that ridesharing companies have with public transit. Public transportation ridership has declined nationwide as travelers have shifted to the ease and comfort of ridesharing. But as more Uber and Lyft drivers take to the streets, cities have grown more congested, and experts warn that it’s not sustainable.

Buses and trains are the most space efficient ways to transport people in cities. And sometimes those modes can be quicker – and much cheaper – than hailing an Uber or Lyft.

You can now buy a ticket to ride on Las Vegas buses through Uber's app.

“It’s a little bit of a risk on Uber’s part,” David Reich, who leads transit at Uber, told CNN Business. “We’re taking riders who are opening the Uber app planning to take an Uber and saying in some situations, taking public transportation is better.”

Lyft started featuring some public transit information in 2018, and made the option more prominent in an app update this fall. It may expand into ticketing like Uber, but hasn’t said when that may happen.

The ridesharing companies say they see themselves as a complement to public transportation, as they both offer alternatives to car ownership, a cultural norm they hope to end.

“We can’t do it alone,” Reich said. “Public transportation is the backbone of how people move about their cities and for Uber to thrive, public transportation has to thrive.”

Reich said Uber’s ticketing partnerships grew out of conversations with transit officials, and gaining a better understanding of their needs.

Tickets bought through Uber will cost the same as if a traveler bought their ticket directly from the Regional Transportation Commission of Southern Nevada, which operates the Las Vegas buses. Uber isn’t receiving a cut of the fare from Las Vegas, but it does have a business partnership with Masabi, a British company that provides the underlying mobile ticketing technology.

Transit experts see one-stop shopping in a single app as a way to help people make well-informed decisions about their transit options and routes. Kevin Krizek, a professor at University of Colorado Boulder, pointed to Helsinki, Finland, which offers a transportation card that gives people access to buses, commuter trains, metro, trams and ferries.

“It just makes it that much easier,” Krizek said. “If there are transit complications they can steer you toward bikes. If there’s not enough bikes they’ll steer you elsewhere.”

In Denver, the <a href="https://www.rtd-denver.com/sites/default/files/2019-08/RTD-Uber <a href="> (UBER)-Masabi%20ticketing%20NR.pdf” target=”_blank”>first city where Uber (UBER) offered public transit tickets, 37,289 tickets were sold in the app in 2019, according to Denver’s Regional Transportation District. Uber (UBER) said it’s seen an average of 15% weekly growth in sales there. Uber (UBER) plans to launch more transit ticketing partnerships in other cities this year.

Denver hasn’t yet studied how the collaboration has affected ridership or customer satisfaction, according to a spokeswoman for the Regional Transportation District. A third of the tickets bought in Denver have been people traveling from its airport to downtown, according to Reich.

“The first thing a Denver visitor might do is open the Uber app,” said Wes Marshall, a University of Colorado Denver professor who studies transit. “You’re going to see there’s a great train that goes right downtown and it’s the best option in terms of time and money.”