By John S. McClenahen There's certainly no sign of a surge in hiring across the U.S. economy. But an uptick in the Conference Board's Help-Wanted Advertising Index, coupled with a continuing relatively low level of new claims for unemployment insurance, suggests that the U.S. labor market is starting to improve. In February, the Conference Board's index stood at 40, up from 39 in January, though just below the 41 of February 2003. "The national labor market has begun to improve, but the small gains only bring us back to year-ago levels," says Conference Board economist Ken Goldstein. However, "the positive news here is that the incremental improvement in want-ad volume comes at the same time that layoffs, as measured by initial unemployment claims, have been edging lower." The New York-based Conference Board, a business research group, surveys help-wanted advertising in 51 newspapers across the U.S. every month.