Americans are spending enough to keep the economy rolling, but don't expect them to splurge unless their paychecks start to grow.

Four years into the economic recovery, U.S. workers' pay still isn't even keeping up with inflation. The average hourly pay for a nongovernment, non-supervisory worker, adjusted for price increases, declined to $8.77 last month from $8.85 at the end of the recession in June 2009, Labor Department data show.

Stagnant wages erode the spending power of consumers. That means it is harder for them to make purchases ranging from refrigerators to restaurant meals that account for most of the nation's economic growth.

Economists blame three factors:

Economic growth remains sluggish, advancing at a seasonally adjusted annual pace of less than 2% for three straight quarters—below the prerecession average of 3.5%. That effectively has put a lid on inflation, which has been near or below the 2% level the Federal Reserve considers healthy for the economy. With demand for labor low, prices not rising fast and 11.5 million unemployed searching for work, employers aren't under pressure to raise wages to retain or attract workers.