It’s also an example of how one smart urban-design decision can have ripple effects. Some residents here grumbled about fewer lights. That said, the stronger new ones turn out to save Detroit nearly $3 million in electric bills. They use aluminum wiring, which nobody wants to strip, discouraging crime. The technology even cuts carbon emissions by more than 40,000 tons a year — equivalent to “taking 11,000 cars off of your streets,” Shaun Donovan, Mr. Obama’s director of the Office of Management and Budget, pointed out at the lighting event, as well as “putting more money in the city’s pockets to do more good things.”

Good things like investing in development beyond the downtown-Midtown core. I met with the city’s new planning and housing chiefs, who outlined a bold agenda to target dense areas, like the one around Livernois Avenue, between Seven Mile Road and Eight Mile Road, the city’s former luxury fashion district. Homegrown entrepreneurs like Rufus Bartell, catering to a young, more urban-minded population, are reviving the avenue. Mr. Bartell and his family have opened nearly a dozen businesses along Livernois, including Kuzzo’s Chicken & Waffles, where he and I convened one recent morning over breakfast. The place was mobbed, as usual.

Businesses like Kuzzo’s pretty much had to shut down by dinnertime during the winter when the lights were out, Mr. Bartell told me. “People didn’t want to go out to eat or shop after the sun went down,” he said. He gestured out the window toward a shop across the street. “I own a store that sells furs and leather goods, with a customer base that skews older. Foot traffic almost fell to zero after dark. Since the lights came on, it’s up 15 percent across this neighborhood.”

Back at Sister Pie, I talked with Shannon Smith, 26, another Detroit native, who said he had grown up in Cody Rouge, an area on the northwest side of the city where getting to and from the bus stop as a teenager was a twice-daily nightmare when streetlights failed. He and other schoolchildren all across town waited in the dark for broken-down buses that often didn’t arrive on schedule.

“I was especially vulnerable whenever it snowed, because the city didn’t clear the sidewalks,” Mr. Smith recalled.