But the mayor, and the region, have a big challenge ahead. Putting in new light rail or even bus rapid transit is costly, and can take away space currently used by cars. And it is difficult to find funding in Tennessee, a state where there is no income tax and municipalities have to depend on sales tax for revenues.

“If we had a dedicated revenue stream right now for transit, we would be building it,” JoAnn Graves, the executive director of the Transit Alliance of Middle Tennessee, told me. “We have not been willing to go into debt to fund any kind of transportation system.”

But, even if the city could find the money for a new light-rail line, would people use it? Like most Americans outside the biggest cities, people in Nashville are accustomed to using their cars. According to Census data from 2009, fewer than 3 percent of workers in the Nashville metro area used public transit to commute to work, making the city less public-transit-friendly than Houston, Richmond, Memphis, Tampa, and Kansas City, to name a few.

Evidence from other cities indicates that even if Nashville somehow finds the money to put into light rail or bus rapid transit, it could be challenging to get people to use those systems. And though transit may reduce congestion temporarily, commuters will return to the roads once they see traffic is down.

In most metro areas of less than 1 million people (Nashville has roughly 659,000), just 1.5 percent to 2.5 percent of residents use transit, according to David Hartgen, a emeritus transportation professor at UNC Charlotte. Many of these places have tried to increase the share of their population that use transit, but few have succeeded.

“It’s an extremely difficult thing to do because we have this minor detail in this country called freedom,” he said. “You can live where you want, you can work where you want, you can commute how you want.”

Even Charlotte, which is seen as a poster-child for public-transit advocates because it invested heavily in transit over the last two decades, has not seen a significant increase in ridership when compared to the region’s astronomical growth, he told me. And, when gas prices go down—as they have in recent months— ridership decreases.

Charlotte came to terms with the idea that it needed to add transit in the 1990s as the city grew, and in 1998 passed a half-cent sales tax to fund transit. A light rail line, the LYNX Blue Line, started running in 2007, and it is currently being expanded. A 1.5-mile streetcar line opened in July of 2015, and the city is planning on expanding it. A regional plan seeks to establish 25 miles of commuter rail, 19 miles of light rail, 16 miles of streetcar, and more buses throughout Charlotte and its suburbs.

But ridership has remained essentially flat, even though downtown Charlotte has grown by about 50 percent in employment, Hartgen says. Average daily ridership of CATS, the Charlotte Area Transit System, peaked at 95,484 in July of 2008 and has hovered around 90,000 ever since; its most recent 2015 figures were down a little, at 84,889. Average daily ridership of LYNX, the light-rail line, jumped to 16,895 when it first started in 2008 and has stayed around there, reaching 17,868 in September.

The case of Charlotte shows that, even when there is transit available, the vast majority of people won’t leave behind their cars and embrace public transportation, Hartgen argues. In many cities, the average commute time by public transit is about twice what it is when driving your own car. And in many cities, including Charlotte, only about 20 percent of the operating costs of a transit line come from ridership; the rest come from government dollars. What's more, Hartgen says, as population increases, a city's transit costs rise much faster than revenues from transit do, ​as the city tries to expand its service to new neighborhoods​. In Nashville, for instance, the population grew 9 percent between 2007 and 2013, while operating costs grew 66 percent.