The purpose of this primer is to assist transportation planners in effectively using archived operations data for developing, analyzing, and evaluating transportation plans and programs. This primer raises planners’ awareness of the opportunities afforded through archived operations data and provides guidance on how to take advantage of that data to expand and improve planning practices. It also identifies innovative applications for archived operations data in planning. This primer aims to help planners and their operations data partners overcome the barriers to obtaining and using data, regardless of whether they are just getting started with using the data or have substantive experience.