Transportation agencies have an opportunity to leverage massive GPS trajectory data to support their analyses and enhance their decision making. However, these data are typically purchased from vendors, which means that transportation agencies must understand their benefits before they decide to spend tens of thousands of dollars on data acquisition. To help transportation agencies better understand the tremendous value of trajectory data, the PI of the project will acquire Utah GPS trajectory data from one of the leading GPS data providers and conduct visual analyses demonstrating applications of trajectory data in various areas of transportation. The analyses will focus on (a) evaluating the data itself by exploring its spatial and temporal coverage, and on (b) using visual analytics to demonstrate potential use of trajectory data in planning, measuring mobility, public transit, and measuring performance. The results of the analyses will be communicated with transportation agencies to help them better understand the value of this type of mobility data in transportation system analyses.