In the week that ended March 31, jobless claims droppedto 357,000—the lowest they have been in four years, according to new numbers from the Labor Department. Pennsylvania posted the biggest drop in claims—1,956—while Texas posted the highest jump—4,185. The steady gains that have been happening since the fall are likely due to fewer layoffs and the strengthening of the labor market, as proved once again by last month's private-sector jobs numbers.