News of the upswing in spending came as the picture for April also changed for the better, suggesting retail sales were likely to support GDP growth in the second quarter.
Sales rose 0.5 percent compared to April to $519 billion, according to the Commerce Department's latest estimate, putting them up 3.2 percent above May of last year.
The result was below forecasts but appeared smaller after April was revised upwards from a decline to a modest 0.3 percent increase.
"This confirms that the main engine of US growth is still humming along and certainly flies in the face of recession fears," Oxford Economics said in an analytical note.
"Looking ahead, buoyant consumer confidence, healthy job creation, tame inflation, lower gas prices, and solid wage growth should support robust household outlays in coming months."
Sales of autos and parts rose a healthy 0.7 percent, reversing a sharp drop in April.
Excluding sales of motor vehicles and parts, retail sales also rose 0.5 percent.
Electronics stores sprang to life, posting a 1.1 percent gain that nevertheless left them 2.4 percent below their level of May last year, when the US economic engine raced under the effects of fiscal stimulus and 2017's tax cuts.
Sales at sporting goods, book and musical instrument outlets rose 1.1 percent but were also well below year-ago levels.
Meanwhile, long-suffering department stores continued their decline, posting losses of 0.7 percent, their biggest month-to-month drop since December.
Online sales continued to march in the opposite direction, rising 1.4 percent, putting them 11.4 percent above May of last year.
The Federal Reserve next week is widely expected to signal its readiness to act should prospects for continued US economic growth deteriorate later this year, but to leave interest rates untouched for the time being.