Beginning in May 2021 many US mappers have participated in a project to harmonize US highway classification between the states and with world-wide practice. Focused on "importance" and network connectivity, the project began with a reevaluation of US-usage of the `highway=trunk` tag and has broadened to address the full network hierarchy and several other classification tags. While striving for national consistency is the ultimate goal, transportation departments in the various states are too diverse in their practices for a one-size-fits all approach. The major work of this project is for local communities to develop state-level guidance that fits their region and can blend with neighboring states and the nation as a whole. This talk will present some background on the project, share the current state of implementation, and discuss future efforts and challenges. This talk was presented at State of the Map US 2022. To learn more about State of the Map US 2022, visit https://2022.stateofthemap.us/ Learn more about OpenStreetMap US at https://www.openstreetmap.us/