As North America's oldest trade union, The United Brotherhood of Carpenters organizational structure served as model for the labor unions that were organized later. The modern labor union consists of a governing national or international body that charters local unions who negotiate with the management of individual companies or contractor associations on behalf of bargaining units made up of workers performing similar jobs. Local unions elect their own officers control their funds and property and elect delegates to represent their interests at the the national level. Craft unions often have intermediate bodies called District or Regional Councils that represent the collective interests of Local Unions within the same city or geographical region. Peter McGuire introduced the concept of the "Walking Delegate," commonly known as a Business Agent who is paid by local to handle grievances, dispatch workers, and enforce the Collective Bargaining Agreement. .