| Country | NMI | DI | Quantity |
| Argentina | INTI | National Commission of Atomic Energy (CNEA) | Ionizing radiation |
| Brazil | INMETRO | Laboratório Nacional de Metrologia das Radiações Ionizantes, IRD (LNMRI/IRD) | Ionizing radiation |
| Observatório Nacional/Serviço Nacional da Hora (ON/DSHO) | Time and Frecquency | ||
| Mexico | CENAM | Instituto nacional de ecología y cambio climático (INECC) | Ozono concentration in ambient air |
| Instituto Nacional de Investigaciones Nucleares (ININ) | Ionizing radiation | ||
| Uruguay | LATU | Administración Nacional de Usinas y Transmisiones Eléctricas (UTE), Montevideo | Electricity and Magnetism. |
| Costa Rica | LCM | Instituto Costarricense de Electricidad (ICE), Laboratorio Metrológico de Variables Eléctricas (LMVE) (ICE-LMVE) | Magnetism, Time & Frequency |
| Laboratorio de Metrologia, Instituto Costarricense de Electricidad (LAMETRO-ICE) | Photometry and Radiometry, Fibre Optics, Wavelength and Length | ||
| Laboratorio de Fuerza del Laboratorio Nacional de Materiales y Modelos Estructurales (LanammeUCR) | Force | ||
| Laboratorio Nacional de Metrología, Grandes Masas y Volúmenes (RECOPE) | Mass from 50 kg to 1000 kg | ||
| USA | NIST | Naval Undersea Warfare Center, Underwater Sound Reference Division (NUWC-USRD) | Sound in water |
| International | IAEA | Ionizing radiation | |
| Canada | NRC | Transcanada | Flow |
| Saint Lucia | SLBS | National Agricultural Diagnostic Facility (NADF) | Chemical Metrology |
| Colombia | INM | CALAIRE- UN | Chemical Metrology |
| Ecuador | INEN | CMEE- Ecuador | Time and Frecquency |
| Costa Rica | LCM | CICANUM – Costa Rica | Ionizing radiation |
