The company blames the closure on the country's low beef cattle herd, the lowest, Cargill says, since 1951.
Cargill says it plans to keep its ground beef plant in Milwaukee operating, employing 200 workers.
As for the 600 who will lose their jobs August 1, when the beef harvest facility closes, the company says those workers can apply for positions at other Cargill facilities, and the firm will hold a job fair in town, next week.
Cargill bought the beef harvest plant in Milwaukee, in 2001. It can process up to 1400 animals a day.
A company, which is based in Wichita, Kansas, owns six similar facilities across the country. They will not be affected.
According to a written statement from Cargill President John Keating: "Closing our Milwaukee beef plant is taking place only after we conducted an 18-month-long analysis of the region’s cattle supply and examined all other possible options. It is unfortunate that we must close any beef plant because of the impact to good people, their families and the community."
Cargill reports employing 143,000 people in 67 countries.