Representatives from 19 U.S. cities and counties signed on to a new initiative Tuesday to reduce greenhouse gases created by vehicles, by pledging to incorporate electric vehicles into their municipal fleets.

It’s a small but symbolic step in the efforts to address climate change, because cutting carbon dioxide pollution from transportation has proven to be one of the hardest parts of that campaign. In fact, emissions from transportation sources like cars and trucks became the biggest source of CO2 pollution in the U.S. in 2016.

Los Angeles Mayor Eric Garcetti announced the initiative as part of the Global Climate Action summit in San Francisco this week, where local leaders are gathering to find ways to fight climate change. Outgoing California Gov. Jerry Brown has championed those endeavors in recent years, especially after President Donald Trump announced he wanted to withdraw the United States from the Paris Agreement on climate change.

Mayor Garcetti has tried to rally cities to the cause, as well, and in 2015 helped found a group of Climate Mayors, which now includes more than 400 city leaders. It's that group that has launched the new car-buying collaborative. Nineteen of those cities have signed on to the new car-buying initiative, so far, although organizers expect more to join. 

“The clean transportation revolution is not a distant vision for the far-off future — it’s a reality staring us in the face, and it’s happening here in Los Angeles and cities across the world,” Garcetti said. “Through this innovative platform, Climate Mayors are sending a powerful message to the global car market: if you build electric vehicles, we will buy them.”

The cities that have promised to buy electric vehicles include Los Angeles, Phoenix, Houston, Cleveland, Pittsburgh and Fayatteville, N.C. Los Angeles County and Ohio's Cuyahoga County also joined the program. All told, they’ve committed to buying 376 vehicles in their first year, with the expectation that their participation will grow in future years from light-duty sedans to include electric buses, trucks and other heavy-duty vehicles.

Lauren Faber O'Connor, the chief sustainability officer for the city of Los Angeles, says the new purchasing agreement came as the result of “unprecedented collaboration enabling cities to electrify our fleets in cost-efficient way. We now have a one-stop solution to do that.”

The effort is several years in the making. Los Angeles and other West Coast cities put out a request for information in 2015 to solicit ideas on how they could convert their collective 115,000 trucks, buses and other vehicles to electric-powered vehicles. The concept intrigued companies enough that 40 manufacturers responded with suggestions. 

For the cities involved, the real hurdle was setting up a system that could capture thethe cost savings of buying items in bulk while also abiding by different cities’ procurement rules. Under the new agreement, cities can lease their vehicles or they can buy the cars, which would allow cities to qualify for federal tax credits that can lower the cost of the vehicles by up to $7,500. The platform will allow cities to buy charging equipment.

More importantly, Faber O’Connor says, city officials will get technical expertise from the Electrification Coalition as part of the new collaborative. The group will help city officials and fleet managers consider things like how many chargers they need to install, what type of telematics to put in the vehicles to monitor them, what range their vehicles can travel between charges and how long vehicles will need to charge.

The program is starting out with already-popular electric models, like the Chevy Volt and the Nissan Leaf, so auto manufacturers and dealerships can better understand the needs of cities, Faber O’Connor says. But with localities adopting more ambitious climate goals -- like Los Angeles Metro’s plan to move its entire bus fleet to zero-emission vehicles by 2030 -- she anticipates that the program will expand too.

“We want to move into medium- and heavy-duty vehicles as soon as we get our legs under us, in order to help jumpstart those markets,” she says.