Traffic into the city is worse than ever, but that could all change if a small percentage of motorists opted for alternative transportation.

“On one metric, we have the worst traffic in the country,” said Chris Dempsey, director of the advocacy group Transportation for Massachusetts, citing the 14 percent of drive time Greater Boston commuters spend in bumper-to-bumper traffic, according to an industry study cited by Dempsey.

In New York City, drivers clock 13 percent of their commuting time in gridlock; it’s 12 percent in traffic jams for drivers in Los Angeles, according to INRIX Global Ranking.

School vacation weeks and Friday morning commutes in the summer feel much lighter because it only takes a 5 percent decrease in vehicle volume to reduce congestion by 20 percent, according to Dempsey.

“This isn’t just a Boston problem, this is an American problem,” said Mayor Martin J. Walsh.

Mayors from other cities across the country, in town for the annual U.S. Conference of Mayors, expressed their gripes with growth and the traffic that comes with it to the Herald.

Mayor Christopher Cabaldon of West Sacramento, Calif., said traffic is a major issue up and down the Golden State.

“Not as challenging as here, but congestion and the effects of congestion on air quality and climate change emissions are a big deal,” he said. “In my city, it’s a major problem that we can’t solve through traditional public transit.”

West Sacramento has just implemented innovative mobility initiatives to get people where they need to go, including micro-transit, a mixed breed between public transit and Uber or Lyft, and bike-sharing systems.

Mayor Greg Fischer of Louisville, Ky., said the city has just completed a $2.5 billion major bridges project, which involved two bridges and an untangling of their expressway. The work reduced what was an average 45-minute commute time to 15 to 20 minutes.

“It’s helped getting through and into town much, much easier but we had a significant problem before then,” he said. “Our commute times are not as bad as you guys.”

Boston is already making a billion-dollar investment into transportation, Walsh said, and wants the federal government to pitch in.

“The federal government really isn’t investing in transportation,” he said. “The Trump administration promised this tremendously huge package and the cost has been shifted over now to states and cities 80 percent.”

City officials created the Boston 2030 plan to meet the demands as they predict the population will exceed 700,000 in less than 12 years. The recent hike in double-parking fines to up to $55 is one way to alleviate some congestion, Walsh added.

“We have to be creative,” he said. “People might criticize us for raising the fines but it’ll cut down on double parking and it will cut down on people parking in loading zones.”

Other solutions, he suggests, include encouraging commuters to take public transportation, using the rental “Blue Bikes” and carpooling.

“I think pushing more people to public transportation is key,” Walsh said.

While Dempsey acknowledged there have been some improvements to public transportation, he advocates for more work to be done.

“It’s still breaking down too often and not running frequently enough,” Dempsey said. “It’s still so unreliable that people are choosing to drive in when the MBTA could otherwise be a very good option for them.”

Walsh said he has a dashboard in his office that tells him the on-time performance of the MBTA.

“Honestly, most days it’s 90-plus percent and I don’t think people have confidence in that,” he said. “We just have to continue to upgrade the system.”

Unbridled growth and traffic were among many topics discussed during the Opening Planning Session at the mayors’ conference.

“This is a super powerful mutual learning cohort. Mayors all fight their individual battles in their cities and are trying to move forward,” Fischer said. “When you come here people have gone through similar challenges … so it helps you expedite your solutions.”