Unemployment rates rose in two-thirds of U.S. cities in May, as steady hiring encouraged more of those out of work to look for jobs.

The Labor Department says rates rose in 243 of the 372 largest cities. They fell in 109 and were unchanged in 20.

Nationally, the unemployment rate rose to 7.6 percent in May from 7.5 percent, as more people launched job searches. The government doesn't count people as unemployed unless they are looking for jobs.

Most of the biggest increases were in cities with large universities, where the end of the academic year likely caused many residents to look for summer jobs. The report isn't adjusted for such seasonal patterns.