Unions’ Month of Wins Obscures Challenge of Gaining New Members

Workers at Deere & Co., emboldened by a tight labor market, turned down a 10% raise to stay on strike. Kellogg Co. workers have now been on picket lines since early October; 60,000 TV and film workers threatened to walk out, too.

Nearly two-thirds of Americans now approve of unions, as the wealth gap widens between corporate executives and the rank-and-file. The Biden administration is seen as the most friendly to organized labor in more than half a century.

But while October’s strikes rode a moment of renewed strength for unions, reversing the decades-long decline of organized labor will require ...