Over 120,000 acres of historic citrus orchards and Hohokam archaeological mounds paved over between 1950 and 2026.
ConsequenceSurface albedo decreased from 0.35 to 0.12, triggering a +8°F nocturnal urban heat island.
THE TEMPORAL TOPOGRAPHY ENGINE
The Palimpsest
What used to be here? USGS has digitized historical topographic maps dating back to the 1880s. Scrub across five survey generations (1895 → 1925 → 1955 → 1985 → 2026) to extract the spatial story: roads abandoned, towns inundated beneath reservoirs, citrus groves paved into freeways, and mountains inverted into open-pit copper mines.
What Phoenix Erased to Become Phoenix: 1895 to 2026
Scrubbing across five epochs of USGS topographic quadrangles reveals the complete disappearance of Hohokam mounds, citrus ranch irrigation grids, and historic rail sidings beneath a 100-mile suburban grid.
33.4484° N 112.0740° W 5 survey generations
1895 / 1:62,500ILLUSTRATIVE SETTING
READING 1 OF 5
1895 Phoenix & Salt River Valley
Agrarian canal oasis surrounded by raw Sonoran desert; unpaved wagon trails aligned with natural arroyos.
Present in 1895
- Hohokam prehistoric canal traces
- Grand Canal headgates
- Maricopa & Phoenix Railroad
Absent from this record
- Sky Harbor Airport
- I-10 Freeway
- Suburban grids east of 16th Street
USGS Phoenix 1:62,500 15-Minute QuadrangleU.S. Geological Survey (Engraved Lithograph)
THEN → NOW
1895 2026
Continuous 4.5-million-resident megalopolis with High-Definition 3DEP elevation contours and satellite orthorectification.
PRESENT IN 2026
- Semiconductor mega-fabs
- Loop 202 complete beltway
- High-density transit corridors
- 99% of original agricultural irrigation groves
What changed. What remains.
READ THE TRANSFORMATIONSThe Central Arizona Project canal constructed in the 1980s cuts a 336-mile concrete aqueduct across the desert to lift Colorado River water 2,400 vertical feet.
ConsequenceAllowed urban sprawl to detach from local groundwater aquifer boundaries.
The Salt River, depicted on 1895 maps as a braided perennial desert river with riparian cottonwood forests, is rendered on 2026 maps as dry sand and gravel mining pits.
ConsequenceUpstream dam impoundments (Stewart Mountain, Roosevelt) eliminated surface flow except during extreme reservoir spill events.