The Detroit company says it sold just over 269,000 cars and trucks last month, matching expectations of industry analysts.
The automaker was led by Chevrolet Equinox midsize SUV. Its sales were up 42 per cent to nearly 29,000. Sales of the Buick Encore small SUV rose 29 per cent to nearly 5,600.
GM's top-seller, the Chevrolet Silverado pickup, posted nearly an 8 per cent sales gain to almost 46,000.
Industry analysts expect total U.S. sales to rise about 6 per cent when all automakers report sales numbers on Friday.