There are 20 Field Operations Offices in the United States that provide centralized management oversight and operational assistance to 327 U.S. ports of entry and 15 preclearance offices. Established geographically by region, Field Operations Offices serve as the spokes of a wheel for CBP Headquarters to distribute key policies and procedures to field staff. Field Operations Offices provide guidance to their regional ports and ensure the dissemination and implementation of core CBP guidelines. These offices also provide for mission support functions within their regions; such as, resource management, equal employment opportunity, labor, employee relations, and other human resources management functions.