Logan Simpson is working with the Tucson Historic Preservation Foundation (THPF) to conduct research and to write a National Historic Landmark District (NHLD) Nomination for Los Barrios Viejos in Tucson Arizona. The nomination examines the history, development, and architectural character of three barrios (neighborhoods) and a historic district in downtown Tucson. These combined areas proposed in the NHLD contain the highest concentration of Sonoran-style adobe architecture found within the nation. The barrios within the NHLD are among the oldest neighborhoods in Tucson. They were ethnically diverse and hold particular significance to the Mexican American communities. The architectural character of the NHLD tells the story of a community that transitioned from a Spanish presidio to Mexican frontier settlement to a modern U.S. city. The nomination is awaiting review by the National Historic Landmarks Committee and will eventually lead to the listing of the barrios as a National Historic Landmark.