Over the year, the country’s largest metro areas have steadily added jobs, the Labor Department said Wednesday.

That growth has expanded the workforce in many places as people come off the sidelines to hunt for job opportunities they might not have seen a year ago, or new arrivals move to where the jobs are.

In some cities, that’s pushed up the jobless rate, if the economy can’t immediately put all those new entrants to work. In the year to June, nonfarm employment rose in all 51 of the U.S. metropolitan areas with a 2010 Census population of 1 million or more. Of those 51, eight saw their unemployment rates creep up.

Some of the cities with higher jobless rates were in the oil patch or reliant on manufacturing, which has been facing headwinds from the strong dollar. Others were metro areas that in June 2015 had some of the lowest jobless rates in the country, suggesting they may have attracted job-seekers from other areas or recent college graduates in the intervening year.

The national unemployment rate in June was 5.1%, down from 5.5% a year earlier. All figures are not seasonally adjusted.

Oklahoma City, Okla., and Houston, Texas, two metro areas with major energy industries, saw their unemployment rates rise, by 0.5 and 0.7 points, respectively. That brought their unemployment rates up to 4.7% and 5.5%.

Rust Belt cities Pittsburgh, Pa., and Cleveland, Ohio, both saw their unemployment rates creep up. Pittsburgh’s rose to 5.8% from 5.5% a year ago. In Cleveland, the jobless rate rose 0.1 point to 5.5%.

Minneapolis, Minn., and Salt Lake City, Utah, both saw their unemployment rates rise, but both cities still had jobless rates below 4%.

The labor-force participation rate rose 0.1 point to 62.7% in June 2016 from a year earlier, the Labor Department reported in early July. Those figures are seasonally adjusted.