Americans earned and spent more in March, but much of the extra money went to pay for gasoline.

Personal incomes rose 0.5% last month and consumer spending increased 0.6%, the Commerce Department reported Friday. But after adjusting for inflation, spending rose only 0.2% and after-tax incomes were essentially flat.

Consumer spending had been expected to post solid gains this year, helped by stronger employment growth and a 2-percentage-point cut in Social Security payroll taxes. But Americans are paying more for gasoline, prompting economists to scale back their growth forecasts.

The national average at the pump on Friday was $3.90 a gallon — 31 cents higher than a month ago and more than $1 higher than a year ago.

Less growth in consumer spending was a big reason the overall economy slowed sharply in the first three months of the year. The 1.8% growth rate was weaker than the 3.1% rate in the previous quarter. Consumer spending is important because it accounts for roughly 70% of economic activity.