That was on Aug. 1, more than five months ago, and since then the workers and their families have been scrounging to make ends meet. Some face foreclosure and utility disconnection notices.

American Crystal has hired more than 900 replacement workers to keep its plants running. Federal law allows employers to hire such workers during a lockout, although they cannot permanently replace regular employees. Employers can pay the replacements lower wages, although as is the case with American Crystal, the companies sometimes need to offer higher wages and help pay for housing to attract replacements.

With many private-sector labor unions growing smaller and weaker, and with public-sector unions under attack in numerous states, some employers think the time is ideal to use lockouts, a forceful approach they were once reluctant to use.

Many employers, though, say they have little choice.

Robert Batterman, a labor lawyer who represents employers, said whether it was the N.F.L. or Sotheby’s, which locked out 43 art handlers in Manhattan last July, “the pendulum has swung too far toward the employees, and the employers are looking in these tight economic times to get givebacks.”

“Employers,” he continued, “are using lockouts because unions are reluctant to do what the employers consider reasonable in terms of compromising. Employers are looking to reset their collective bargaining relations.”

After being out of work since Aug. 1, Paul Woinarowicz, a warehouse foreman employed at American Crystal Sugar for 34 years, sees another rationale for lockouts.

“It’s just another way of trying to break the union,” said Mr. Woinarowicz, a member of the bakery and confectionery workers union. “People here in the Red River Valley are really mad at American Crystal. It was just like a knife stuck in your heart.”