Unemployment rates fell in almost all large U.S. cities in April, helped by stronger hiring. The gains show the job market is improving throughout the country.

The Labor Department said Wednesday that unemployment rates declined in 344 of the 372 largest metro areas. Rates rose in just 17 cities and were unchanged in 11.

The U.S. unemployment rate dropped in April to a four-year low of 7.5 percent, down from 7.6 percent in March. Employers have added an average of 208,000 jobs each month in the past six months. That’s up from just 138,000 in the previous six.

The metro unemployment data aren’t seasonally adjusted for trends like the hiring of summer employees in coastal cities. As a result, it can be more volatile than the national data.

For example, some of the biggest drops in April unemployment took place in coastal cities. The rate in Salinas, Calif., fell to 10 percent from 12.5 percent in March. In Ocean City, N.J., unemployment declined to 13.8 percent last month, from 17.1 percent in March. Both declines likely reflected a pickup in seasonal hiring.

Still, the broader trend across cities has improved in the past year. Overall, 48 cities had rates of less than 5 percent. That’s up from 32 a year earlier. Only 26 cities had rates of 10 percent or higher, down from 41 in April 2012.

Midland, Texas, posted the nation’s lowest rate, at 3 percent. It was followed by Iowa City, Iowa, and Bismarck, N.D., both at 3.1 percent.

Yuma, Ariz., had the nation’s highest rate, at 30.3 percent, followed by El Centro, Calif., with 24 percent. Both cities have long had the highest rates in the country. They are adjacent and have heavy populations of migrant farm workers.