State legal metrology laboratories are custodians at the State level of measurement standards that serve as the basis for ensuring equity in the marketplace and as reference standards for calibration services for indigenous industry. As part of its program to encourage a high degree of technical and professional competence in such activities, the National Institute of Standards and Technology (NIST) Office of Weights and Measures (OWM) has developed performance standards and formalized procedures for Recognition of State legal metrology laboratories on a voluntary basis. Certificates of Metrological Traceability are issued upon evaluation of the laboratory's ability to make reliable metrological measurements (principally mass, volume, length, and temperature).
The OWM Laboratory Metrology Program consists of six formal Regional Measurement Assurance Program (RMAP) groups as shown in this map. The RMAPS include the Caribbean Measurement Assurance Program (CaMAP), the Southwestern Assurance Program (SWAP), the Southeastern Measurement Assurance Program (SEMAP), the Northeastern Measurement Assurance Program (NEMAP), the MidAmerica Measurement Assurance Program (MidMAP), and the Western Regional Assurance Program (WRAP). Participants include weights and measures laboratories and other government laboratories, such as Los Angeles County (LAC) and the U.S. Department of Agriculture, Grain Inspection Packers and Stockyards Administration (USDA-GIPSA).