ELGIN, Ill. — Despite the concern about China snatching American technology, the Chinese company slated to buy Waltham battery maker A123 Systems Inc. has been a fixture in US manufacturing for two decades, building a base in the Midwest and saving thousands of old-line factory jobs at a time when local businesses were folding.

Wanxiang America Corp., the North American arm of a Chinese conglomerate, owns several auto parts factories in the United States, and provides parts for one out of three cars manufactured in America. It is a major property owner in the Midwest, leasing to Walgreens drugstores among other businesses, and its growing presence in the alternative energy business includes a large stake in GreatPoint Energy of Cambridge.