DETROIT — General Motors, Ford Motor and Chrysler on Monday said their sales in the United States rose last month, signaling that the auto industry was a bright spot amid the nation’s economic uncertainty.

Chrysler reported the biggest gain, 27 percent, while G.M. sales were up 20 percent and Ford’s rose 9 percent. Nissan said its sales increased 25 percent. Analysts said they expected nearly all carmakers to report sales increases for September and estimated that total sales for the industry climbed to the highest level since April. September was the first month since the March earthquake and tsunami in Japan that Toyota and Honda plants were running at full capacity.  Read more