NEW YORK (CNN/Money) - With closets around the country loaded up to the rafters, you have to wonder if U.S. consumers have hit their upper limits.

One of the few pluses for the economy over the past few years was that Americans looked past a tough business climate, sagging stocks and a deteriorating employment picture and just kept spending.

Lately that spending has gone into overdrive, with consumers shelling out cash at an unprecedented rate. According to the Commerce Department, spending on durable items (things that last a while, like cars and washing machines) was up an annualized 32 percent in August from where it was in February. Strip out autos, and spending on durables was up 21 percent. There have never been such large gains before.

Economists tell us to never underestimate the ability of Americans to spend and then go into hock to spend more. One portfolio manager we know likes to say that having a teenage daughter is very helpful for understanding U.S. consumer behavior.

But surely there is some threshold above which the consumer can't go. We're talking about an America where there are now more registered vehicles than licensed drivers. How long can the auto makers and other manufacturers keep on offering such generous incentives to keep people spending, hoping, as the old joke goes, to make it up on volume? And how many $60 nose-hair trimmers does dad need?

Economists expect at least some sort of giveback in the months to come. They point out that the effects of the refinancing boom are beginning to wane, as are the effects of the tax cut. If all goes well, other areas of the economy, like business spending, will pick up where the consumer left off.

"The consumer's role in this upturn is going to be the opposite of [his] role in the downturn," said Citigroup senior economist Steven Wieting.

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At the least, this will mean growth will be more languid than it usually is during the initial stages of economic expansion. And unless the baton is passed from to the consumer to other areas of the economy smoothly (a doubtful prospect) it could also mean that at some point soon we could be in for another bout of weak economic reports. That would set investors to question the recovery.