The more powerful the unions became, the more employers came to fear them. Management refused to recognize unions as representatives of the workers. Many employers forbade union meetings, fired union members, and forced new employees to sign “yellow-dog contracts,” swearing that they would not join a union.
Finally, industrial leaders, with the help of the courts, turned the Sherman Antitrust Act against labor. All a company had to do was say that a strike, picket line, or boycott would hurt interstate trade, and the state or federal government would issue an injunction against the labor action. Legal limitations made it more and more difficult for unions to be effective.
Despite these pressures, workers—especially those in skilled jobs—continued to view unions as a powerful tool. By 1904, the AFL had about 1,700,000 members in its affiliated unions; by the eve of World War I, AFL membership would climb to over 2 million.