Abstract The United States (US) Environmental Protection Agency's (EPA) Greenhouse Gas (GHG) Mandatory Reporting Program (GHGRP) is designed to collect accurate and timely facility-level emissions data that might be used by policy makers to support sound climate policy decisions in the future. After reviewing the US Inventory and the expected improvements under GHGRP, we find that the benefits of GHGRP are minimal and quite possibly zero while the cost of implementation is relatively high, that the stated goal of reducing emissions uncertainty is not met by the program in its current form, and that the additional emissions data to be collected is likely not needed given the ongoing non-committal environment of US GHG regulation. Our review also highlights the need for EPA to make its US Inventory GHG models accessible to the public, which would enable a more thorough review of its assumptions and methods by the broader scientific community.