Americans’ confidence in employment prospects is soaring as the labor market tightens. The latest proof: A record number are voluntarily quitting to seek better jobs.

Some 3.56 million workers left positions in May, the most in data back to 2000, and up from the prior month’s 3.35 million, Labor Department data showed Tuesday. That pushed up the quits rate, which measures quitters as a share of employed people, to a 17-year high of 2.4 percent from 2.3 percent. With more workers feeling assured of finding better employment, sustained wage gains may soon follow.

The latest jump is sure to be closely watched by Federal Reserve policy makers as they monitor for signs of upward pressure on worker pay that may feed overall inflation. In another bullish sign, the gap between vacancies and the number of unemployed widened to 573,000 in May, a sign there’s potentially work available for every jobless person in America.