CHICAGO — MillerCoors announced Monday that it would close a longtime facility in Eden, North Carolina, the first to brew Miller Genuine Draft, because of a prolonged sales decline and the plant’s relative proximity to another MillerCoors location in Virginia.

The plant’s closing in September 2016 will mean about 520 people are laid off, according to MillerCoors spokesman Marty Maloney. The company would help employees with “workforce training and job search assistance,” he said.

The news comes less than a week after Chicago-based MillerCoors announced its acquisition of San Diego-based Saint Archer Brewery, making it the latest large beer company to expand its craft beer offerings through acquisition. Volume sales of domestic mainstream beers have steadily declined in recent years as craft and import beers have surged.

Since MillerCoors formed seven years ago, a joint venture of Molson Coors and SABMiller, volume has declined almost 10 million barrels, according to a company news release, which attributed that loss to “economic challenges, an explosion of choice and fragmentation within the beer business, and a dramatic change in the way consumers engage with brands.”

The Eden brewery is the first announced closing since the joint venture.