The world reached a huge milestone in 2008 when, for the first time in history, the majority of the human race began living in cities.

Three years later, The Atlantic reached a milestone of its own. The well-known magazine of ideas and reportage launched a standalone site, Atlantic Cities, aimed at chronicling this global shift toward urbanization. The editors had lofty ambitions at the start, pledging to create a "destination for urban wonks and curious consumers alike."

Now, five years to the week after its initial launch, The Atlantic is putting some additional muscle behind those ambitions. On Tuesday, The Atlantic announced that the site, now known as CityLab, would gain a dedicated general manager in Robert Bole and an expanded staff as part of a push to double both audience and revenue.

The investment in CityLab was prompted by a belief that the site could grow quickly with a little push from its parent company, said Bob Cohn, The Atlantic's president.

"There's a sense that the editorial content of CityLab has been excellent and that we have underperformed in paying attention to the promise of CityLab as a business," Cohn said. "So we want to focus on growing our partnerships, growing distribution, growing revenue, adding editorial content and resources as part of the strategy."

The new general manager of CityLab will be Robert Bole, the former director of innovation for the Broadcasting Board of Governors and a sometime advisor to The New York Times and The Atlantic. He also has a master's degree in urban planning, a qualification mix that makes him a good fit for the site, Cohn said.

In addition to Bole, CityLab will also gain a full-time developer and a marketing staff, Cohn said. The site will increase its editorial staff, too. All told, the initial expansion will include a "half-dozen" people, with more to follow if the investment bears fruit.

Until now, CityLab has had its own editorial team but relied on staffers from The Atlantic for everything else. That will now change, Cohn said.

"Everyone else has been mixed in with The Atlantic's resources," Cohn said. "Sales. Marketing. Product. Technology. Overall leadership. The thinking here is to give it its own strong team."

CityLab garners between 2 and 4 million monthly unique visits, which would put its target audience goal somewhere between four and eight million. The revenue growth will likely come from a combination of national advertisers — think JPMC, Siemens and Xerox — and grants from foundations that would subsidize coverage.

With today's investment, The Atlantic is betting that CityLab will perform better as a standalone site. It's the opposite of a decision made early 2014 to fold its news and opinions aggregator, The Wire, into the The Atlantic's main site. In recent years, leaders at the company have occasionally wondered whether to double down on their vertical strategy or merge brands with their primary digital property, Cohn said.

CityLab will live on as a separate site largely because the content is distinctive from The Atlantic's usual offerings, he said.

"Occasionally there are stories on CityLab that migrate over to TheAtlantic.com because there's general interest and they're so good," Cohn said. "But usually a successful CityLab story is going to have deeper and narrower appeal to a specialized audience."

Correction: A previous version of this story referred incorrectly to a major advertiser for CityLab. It is JPMC, not JP&C. This story also misquoted Cohn. He referenced TheAtlantic.com, not Atlantic.com