ST. LOUIS — Worries over immigrants potentially taking jobs from native-born Americans run high in parts of the nation, but some U.S. cities are taking a different view: Wooing immigrants can reverse long-term declines in population.

Cities, mostly in the Midwest and mid-Atlantic states, are betting that attracting foreign-born residents can spur business creation and revive neighborhoods. Steps vary from proclamations welcoming immigrants, to adding staff focused on attracting newcomers and translating government websites, to efforts to connect international students with local companies.

“We’ve had neighborhoods decimated by population loss, and the only way we rebuild is by bringing new people here,” said Pittsburgh City Councilman Bill Peduto, a mayoral candidate who includes attracting immigrants in his campaign platform.

The efforts are most evident in the Rust Belt, a region historically strong in manufacturing that a century ago was a leading destination for immigrants. During the fresh immigration surge in recent decades, however, newcomers largely bypassed Detroit, Cleveland and St. Louis as manufacturing there—and other cities in the region—dwindled. They opted instead for cities such as Phoenix and Dallas.

Between 2000 and 2011, the Rust Belt, stretching from western Pennsylvania to the Mississippi River, was home to 18 of the 25 fastest-shrinking cities in the U.S. Their proportion of foreign-born residents, moreover, lagged well behind the national average of about 13%, with less than 5% in some cities. So while Pittsburgh and Dayton, Ohio, for instance, bled residents, they also missed out on a national immigrant boom that saw the population of foreign-born residents in the U.S. grow by 25% over the last decade, compared with an 8% rise in native-born residents.

In St. Louis, the local economic-development agency in March hired Betsy Cohen, a former executive for the Purina unit of Nestle SA,NESN.VX +0.52%to launch the city’s first programs to draw the foreign-born. The city’s population has dropped by nearly two-thirds to 318,000 residents since peaking in the 1950s.

On a recent morning, with a Spanish lesson loaded into her car’s CD player to brush up on language skills, she crisscrossed the city, meeting with business leaders and town managers from the St. Louis suburbs. “Imagine this: By 2020—with your help, with my help—we have the fastest rate of immigrant growth,” Ms. Cohen told a group of Asian-American business leaders over coffee and muffins.

Such efforts contrast with developments in Arizona, Alabama and some other states, where concerns that illegal immigrants could take jobs from native-born workers and drive up government costs have helped fuel a push for tougher immigration enforcement. Action at the state level has slowed amid legal challenges and complaints from business leaders and civil-rights activists, and now the debate has largely shifted to the federal level, where the U.S. Senate is weighing an overhaul of immigration policy.

Economists disagree over how much new arrivals complement the existing labor force or displace existing workers and drive down wages. Supporters of recruitment efforts in the Rust Belt say they must be careful to avoid pushback from native-born residents who might feel they are being left behind.

According to researchers, newcomers’ decisions on where to settle are largely driven by family connections and the availability of work, complicating efforts by cities where growth rates are low. “It is mostly the economic opportunities, and once the pioneers go and find jobs, the social networks kick in,” said Jeanne Batalova, a senior policy analyst at the Migration Policy Institute, a nonpartisan think tank in Washington, D.C.

As Ms. Cohen seeks to draw immigrants to St. Louis, professors at universities in the city are preparing a study of steps other cities have taken. Some include launching an online outreach program designed to knit together existing ethnic groups—thus providing a magnet for newcomers—and starting a welcome center to help with training and language skills.

Jack Strauss, a St. Louis University economics professor, said immigrants the city attracts will tend to be either highly skilled workers companies struggle to find or low-skilled workers willing to do jobs most native-born residents won’t. “Our businesses need both workers and consumers,” he said.

Detroit is one of the furthest along in its effort, with the nonprofit Global Detroit raising more than $5 million, mostly from private sources, for immigrant programs. Three employees are working on keeping international students from leaving, running campus events and producing webinars to help potential employers with the visa process. The group also launched an 11-class course on the basics of running a small business.

In Pittsburgh, local nonprofit Vibrant Pittsburgh recruits highly skilled foreigners at national conventions, sends frequent emails to immigrant-community groups about Pittsburgh job opportunities and, since June, has given out $100,000 in grants to 25 local community groups that focus on immigrants.

Teanna Medina, a 25-year-old Cuban American, had already bought a plane ticket to Brazil for a job last year after receiving a master’s degree from the University of Pittsburgh. Then, Vibrant Pittsburgh helped her find a job in the area and she decided to stay. A few months later, her 41-year-old cousin, Lazaro Rodriguez, crossed the Mexican border as a Cuban refugee with about 20 others. “A lot went to New York and a lot went to Miami,” Ms. Medina said. “But he was the only one that came to Pittsburgh.”

Write to Mark Peters at [email protected] and Jack Nicas at [email protected]