Unemployment rates fell in 24 states in January and rose in just eight, the latest evidence that hiring is strong across the country.

The Labor Department says jobless rates were unchanged in 18 and in Washington, D.C.

North Dakota has the nation's lowest jobless rate, 2.8 percent, a sign that falling oil prices had yet to cause major layoffs in a state that has benefited from an energy boom. Mississippi and Nevada had the highest unemployment rates, 7.1 percent.

Nationwide, employers have added 3.3 million jobs over the past year. Unemployment across the nation dropped to 5.5 percent in February from 6.7 percent a year earlier.