This project examines changes in the spatial pattern of warehousing and distribution (W&D) activities for the four largest California metropolitan areas: Los Angeles, San Francisco, Sacramento, and San Diego. W&D activities are decentralizing in response to rising land values and scale economies. Ultimately, this project seeks to understand whether these spatial shifts result in more truck vehicle miles traveled (VMT), or whether the efficiencies gained by larger scale operations allow offsetting savings, such as enabling the use of larger trucks or achieving higher average load factors. Understanding how these shifts are affecting truck VMT is essential for developing effective policies for managing truck VMT and their associated emissions. However, there is no good source for tract or zone level truck flow data, or for intra-metropolitan truck origin-destination data. As a first step, we focus on accessibility. From the literature on passenger travel, we know that travel distance is related to accessibility. Thus, changes in accessibility to goods markets should be a proxy for goods travel distance, all else equal.