One park held the whole map for 18 years — by 2020, 63 parks split the country, seven of them claimed in a single day

Asked:

“show me a voroni diagram of National Parks in the USA (a Gravity Map) with regions being assigned to closest national park. also show me a timeline of how the map changes as new national parks were established over time”

All 63 congressionally designated U.S. national parks, from Yellowstone (March 1, 1872) to New River Gorge (December 27, 2020). Every point on the map is coloured by its nearest park; the tessellation redraws at each of the 53 distinct designation dates. California ends with 9 parks, Alaska with 8.

· active parks

added on this date cell colour = era the nearest park was designated: 1872–1919 1920–1959 1960–1989 1990–2020

This is a point-based nearest-park model — each cell contains the land closer to that park's representative point than to any other — not an NPS jurisdictional boundary map. Cells are clipped to the displayed U.S. land extent; the contiguous states, Alaska and Hawaii are tessellated separately within their own panels so the insets do not distort distances. American Samoa and the U.S. Virgin Islands each hold one park, listed below the map.

Cumulative parks by designation date

Yellowstone was the only national park for 18 years, until Sequoia and Yosemite arrived within six days of each other in 1890 — simple.wikipedia.org

December 2, 1980 is the largest single jump: seven Alaska parks — Gates of the Arctic, Glacier Bay, Katmai, Kenai Fjords, Kobuk Valley, Lake Clark and Wrangell–St. Elias — entered at once, lifting the count from 41 to 48 — simple.wikipedia.org

1919 doubled the East's presence: Acadia and Grand Canyon on February 26, Zion in November — three parks in one year — simple.wikipedia.org

California leads with 9 parks, Alaska has 8, Utah 5; the newest park, New River Gorge in West Virginia, joined December 27, 2020 — simple.wikipedia.org

All 63 parks

Park	State / territory	Designated	Lat, lon	Source

Point-based gravity model of the 63 current congressionally designated U.S. national parks: one representative coordinate per park, 63 rows, extracted from the complete park table on Simple English Wikipedia and checked against the English Wikipedia list and NPS park-anniversary dates during research. Dates are national-park designation dates, not earlier monument status. Voronoi cells are computed in projected map space (Albers equal-area families) separately for the contiguous states, Alaska and Hawaii, and clipped to land; American Samoa and the U.S. Virgin Islands hold one park each and are noted in text. 53 distinct designation dates drive the timeline.