In Allen-Bradley Local No. 1111, etc. v. Wisconsin Employment Relations Board, 315 U.S. 740, 62 S.Ct. 820, 86 L.Ed. 1154 (1942), the Court held that the National Labor Relations Act did not preclude state action restraining mass picketing, obstructing entrance and egress from the employer's factory and obstructing public roads and threatening injury to employees desiring to work. The Court states: "We agree with the statement of the United States as amicus curiae that the federal Act was not designed to preclude a State from enacting legislation limited to the prohibition or regulation of this type of employee or union activity. The Committee Reports on the federal Act plainly indicate that it is not `a mere police court measure' and that authority of the several States may be exerted to control such conduct. Furthermore, this Court has long insisted that an `intention of Congress to exclude States from exerting their police power must be clearly manifested'. " (315 U.S. 740, 748-749, 62 S.Ct. 820, 825.)