Unemployment rates fell in half of the 50 U.S. states in May, led by big declines in California and New York, the two most populous states, the government reported Friday. The Labor Department said unemployment rates rose in 17 states and were unchanged in eight states last month. North Dakota, experiencing a shale-energy boom, had the lowest unemployment rate at 3.2 percent. Nevada, whose tourist city of Las Vegas has struggled since the 2008 financial crisis, had the highest at 9.5 percent. Employers added jobs in 33 states last month, the report said. Nationally, the economy added 175,000 jobs in May, while the unemployment rate rose slightly to 7.6 percent, the department reported a week ago.