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Colorado · Indigenous homelands, borderlands and the Centennial State

A broad history of the lands now called Colorado, from ancient habitation and ancestral Pueblo communities to Spanish and Mexican borderlands, U.S. conquest and settlement, statehood, extractive industry, labor conflict, conservation and modern public choices.

The modern rectangle is a geographical frame, not an ancient political unit. The Louisiana Purchase covers only part of it; Mexican territory, Texas claims and U.S. territorial organization have different extents. Indigenous nations are continuing peoples and governments. Mesa Verde migration does not mean Pueblo extinction, and nineteenth-century removals do not mean all Utes left Colorado.

The account follows Hispano settlement in the San Luis Valley as well as Front Range growth. Gold and silver share space with molybdenum, coal, steel, railways, farming, water allocation, military institutions, education, recreation and civil rights. Sand Creek, Ludlow, Amache and their later preservation histories receive separate treatment rather than being folded into a triumphal settlement narrative.

Useful windows: 500–1500 for ancestral Pueblo life; 1760–1900 for borderlands, treaties, mining and statehood; 1880–1935 for labor and extractive economies; 1940–2025 for defense, tourism, rights and public policy. The all-time overview spans deep prehistory, so zooming is important.

Reading tools

Use Separate by tags to compare these overlapping strands: Hispano and Chicano histories, Indigenous histories, Spanish and Mexican periods, agriculture, archaeology, architecture, borders and government, culture and education, disasters, environment, exploration, heritage and conservation, industry, labor, mining, public finance, rights and citizenship, settlement, technology, tourism, trade, transport, treaties and displacement, violence and memory, war and defense, water. Expand moments for evidence, image credits and explanatory cards. Undated cards explain concepts without inventing new dated events. Period bands are editorial guides and intentionally overlap. Directional connections have written explanations; other arcs are thematic reading paths, not automatic claims of causality.

Dates and evidence

Proleptic Gregorian BCE/CE calendar, UTC plotting coordinates. A year-only date uses January 1 as an anchor, not an asserted exact day; a month-only date uses its first day. There is no historical year zero. Early Irish Julian-calendar events generally use year-only anchors rather than silently reusing an Old Style day as Gregorian. Broad and approximate dates have presumptive outlines. A coarse year does not claim that an event happened at midnight on January 1. Research cutoff: 3 November 2026; the newest selected events are from 2024. This is a substantial survey, not an exhaustive county-by-county or person-by-person history.

Sources prioritize original treaties, statutes, constitutional documents, archival records and witness collections, supported by tribal histories, public archives, museums, universities, historical societies and institutional chronologies. Each dated event links the evidence used. Institutional summaries can contain shorthand or errors; dates are distinguished from modern commemorations, and contested claims retain qualifications. Witness collections require evaluation of perspective, provenance and corroboration. The selection does not imply every linked source or image is freely licensed.

Reusable images

The timeline cover, key-moment icons and period backgrounds use credited public-domain, CC0 or Creative Commons media permitting reuse. Modern photographs, later paintings, reproductions and memorials are explicitly identified rather than presented as contemporaneous depictions. Backgrounds are thematic illustrations. The app uses duration backgrounds for periods and moment icons for individual events. No changes beyond thumbnail scaling. Image rights remain those stated in each file record.

74 moments · 10000-01-01T00:00:00Z BCE – 2024-02-15T00:00:00Z CE · by @athan · @athan

Rocky Flats begins nuclear-weapons component production

  • war and defense
  • industry
  • environment

**Historical setting:** 1952 · Colorado and the surrounding region. The plant near Denver becomes part of the U.S. nuclear-weapons complex. Plutonium handling creates risks beyond ordinary industrial production. Later contamination concerns, investigations and cleanup make the site a continuing environmental and public-trust issue. **Historical date:** 1952. **Date precision:** year. Proleptic Gregorian BCE/CE calendar, UTC plotting coordinates. A year-only date uses January 1 as an anchor, not an asserted exact day; a month-only date uses its first day. There is no historical year zero. Rocky Flats connects the Denver area to a national weapons-production network. Working with plutonium introduces specialized industrial hazards and raises questions about the movement and control of radioactive material. The later history of shutdown and cleanup follows from the responsibilities created by production, extending the site’s significance beyond its operational years. **Sources:** - [Rocky Flats Site, Colorado | Department of Energy](https://www.energy.gov/lm/rocky-flats-site-colorado)

Date precision
year
Coordinate convention
Proleptic Gregorian BCE/CE calendar, UTC plotting coordinates. A year-only date uses January 1 as an anchor, not an asserted exact day; a month-only date uses its first day. There is no historical year zero. Early Irish Julian-calendar events generally use year-only anchors rather than silently reusing an Old Style day as Gregorian.

Sources

Related

Open Rocky Flats begins nuclear-weapons component production in the timeline