It was quite a strong summer for the American economy. The question now is how it will hold up over the months ahead.

That’s the main thing to take away from Thursday’s report on gross domestic product for the third quarter.

Overall gross domestic product growth came in at a 3.5 percent annual rate, better than the 3 percent analysts had forecast. It is hardly the strongest result of recent years; that would be the second quarter of this year, with a gaudy 4.6 percent growth rate.

But the results look even better if you take out the fluctuations in business inventories that can make G.D.P. bounce around but don’t really send meaningful signals about the underlying trend of growth in the economy. Looking at final sales, a measure of growth that excludes inventory swings, the economy grew at a 4.2 percent annual rate in the third quarter, the best since the final months of 2010.