Union shop is a form of union security in which the company can hire nonunion people, but they must join the union after a prescribed period of time and pay dues. (If they do not, they can be fired). These account for about 73% of union contracts. Unions and employers also tend to negotiate variations of the union shop (for instance, letting older workers quit the union when the contract ends).
Union shop means agreements stipulating that a company’s new employees must join a union within a certain number of days after being hired in order to keep their jobs.