In my experience, the whole “Midwestern nice” thing can be overstated; but not when it comes to Kansas City. Step off the KC Streetcar (as it is officially known) and look around as if you don’t know where you are going and a passer-by will stop and ask where you’re trying to get to. Sport that expression while you’re still riding it and someone sitting across the aisle from you will do the same thing. Ask them how they like the streetcar and they will tell you, sincerely and in a fair bit of detail. And they do like it. They ride it. The city — which has a population just under a half-million — projected one million riders in the streetcar’s first year; it got twice as many by day 364. A year later that figure exceeded four million.

No one would have predicted such a phenomenon as recently as the beginning of this decade. Back then, Mr. James recalled, “things were slow here. People were depressed. They didn’t believe the city could do things.”

But then Kansas City won a lottery of sorts: In the spring of 2011 — just as Mr. James was starting his first term as mayor — Google announced that it would be inaugurating its broadband internet and television service, Google Fiber, there. “That was a big boost,” Mr. James recalled. “Google was putting us on the map — we could leverage that.”

They did. The streetcar — which made its first run on May 6, 2016 — wasn’t by any means the only element of downtown’s revitalization, but it was perhaps the boldest, and certainly the most dynamic. “It’s been a tremendous catalytic thing,” Mr. James said. “It’s created much more flow—more profits for businesses downtown, more foot traffic.” In the streetcar’s first year of operation, revenue from sales taxes along its route — an area known as the Transportation Development District, or T.D.D. — rose 54 percent, as opposed to 16 percent citywide.