In Pittsburgh, dozens of churches once supported a population of nearly 700,000 after the arrival of Czech, German, Irish, Italian and Polish immigrants in the early 20th century.
With the collapse of the steel industry, however, the city lost an estimated 250,000 people by 1980. From 40 percent to 50 percent of them were Catholic, said the Rev. Ron Lengwin, spokesman for the Diocese of Pittsburgh.
"We lost a large number of people," Lengwin said. "And the population has continued to dwindle."
Read more: Migration causing Pittsburgh congregations to dwindle - Pittsburgh Tribune-Review