Tucson’s development 1886–2002. These four figure-field drawings, all drawn to the same scale, illustrate the shift from the human-scaled streets, blocks and buildings of the traditional city to the car-scaled arterials and sprawling megablocks of urban renewal.

(above) An 1890 bird’s-eye view shows Tucson’s traditional urbanism. The private outdoor space typically found at the center of each block can be seen in the foreground. The continuous height and scale and the inherent density of the urban fabric define the void of the public plaza and the public street.

(above) Convent Street in the 1890s. The public right-of-way is defined by simple, one-story adobe buildings with rustic entrances and windows facing the street. Thick adobe walls kept interiors cool in the summer while the zero-setback relationship to the street created shade for pedestrians. The continuous wall of dwellings directed one’s gaze to St Agustín Cathedral at the terminus of Convent Street. Image courtesy of the Arizona Historical Society/Tucson.

(above) Congress Street, ca. 1897, showing the initial stage of Tucson’s modernization. Two-story brick buildings began to replace adobes but still obeyed the rules of traditional urbanism. Built to the sidewalk’s edge, they defined the public right-of-way with stately facades and large shop windows. Awnings over south-facing sidewalks sheltered pedestrians in the summer. Image courtesy of the Arizona Historical Society/Tucson.

(above) Bird’s-eye-view of Broadway, 1910. The urban characteristics of pre-renewal Tucson had changed little although recent architecture had become more eclectic. The urban fabric still consisted of well-defined streets and public spaces and prominently placed public buildings. Image courtesy of the Arizona Historical Society/Tucson.

(above) Stone Avenue, ca. 1927. A traditional pedestrian-oriented, mixed-use city still functioned well despite the introduction of the automobile and the trolley, both of which shared the right-of-way with pedestrians. Image courtesy of the Arizona Historical Society/Tucson.

(above) A 1930s’ view of Stone Avenue shows that traditional urbanism could support larger buildings. The 11-story Pioneer Hotel stepped down from the tower to the height of the surrounding one- and two-story buildings. The ground floor housed several stores and a restaurant, maintaining the street’s uninterrupted retail continuity. Image courtesy of the Arizona Historical Society/Tucson.

(above) Downtown in the 1970s. The street grid abruptly ends at the Convention Center’s perimeter, an area of excessively wide streets and parking lot sprawl. Important streets were severed by the Convention Center block, discouraging pedestrian access and disrupting traffic flow. Image courtesy of the Arizona Historical Society/Tucson.

(above) The Convention Center and its enormous parking lot in 2003. Sprawling over 35 acres, the only viable way to navigate to, from and around the Convention Center is by car. Pedestrians and automobiles are segregated: cars relegated to parking lots and pedestrians to landscaped pathways and the leftover spaces between buildings.