By The Associated PressThe number of Americans seeking unemployment aid rose last week, though the job market has been improving the past few months. Applications last week increased by 16,000 to a seasonally adjusted 357,000, the Labor Department reported Thursday. The four-week average, a less volatile measure, rose to 343,000, not much more than the five-year low of 340,750 reported the previous week. Claims are a proxy for layoffs, and they've come down steadily since November. Here are the states with the biggest changes in unemployment aid applications. The state level data are for the week ended March 16, one week behind the national numbers. States with the biggest increases: California: Up 3,007, due to layoffs in services. Virginia: Up 1,165, due to layoffs in manufacturing. States with the biggest decreases: Pennsylvania: Down 2,497, due to fewer layoffs in the construction, entertainment, lodging and food service, professional, scientific and technology and transportation industries. New York: Down 2,116, due to fewer layoffs in construction, professional services, scientific and technology and transportation industries. Georgia: Down 2,023, due to fewer layoffs in the manufacturing, administrative and support services, construction and trade industries. North Carolina: Down 1,340, due to fewer layoffs in the commercial machinery, computer equipment and construction industries. Ohio: Down 1,192, due to fewer layoffs in manufacturing. Michigan: Down 1,092, due to layoffs across all industries. Kentucky: Down 1,007, no reason given.