For millions of Americans, the golden years are looking more like dross. In July more than 1 of every 3 people age 55 and older was working or seeking work, the highest proportion since 1974, according to the U.S. Bureau of Labor Statistics. The graying of the work force is due in part to the double blow that retirement portfolios have suffered over the past few years, says outplacement firm Challenger, Gray & Christmas. Stock-market losses and low returns on fixed-income investments are forcing retirement-age people to either continue working or head back to the trenches.