Segregation simulator

Schelling City

Thomas Schelling's 1971 dynamic model of residential segregation. Every one of the 360 agents is content with just 40% same-type neighbours - nobody wants a divided city - yet the city divides anyway. Watch a mild individual preference harden into a segregated whole.

Run parameters

grid 20x20type A 180type B 180 empty 40tolerance 0.40seed 1

Legend

Type A Type B Empty

The result

Happy 0.7361 -> 1.0000

Segregation index climbs 0.5080 -> 0.8429 (+0.3349, a 65.9% rise) across 14 rounds of purely local, individually-rational moves.

The model

A cell moves to a random empty cell whenever fewer than 40% of its occupied neighbours share its type. Deterministic from seed 1 - the same city every run.

Initial city

happy 0.7361 · segregation 0.5080

Converged city

happy 1.0000 · segregation 0.8429 · 14 rounds

The two 20x20 cities are painted from the deterministic run. Enable JavaScript to render the grids and the convergence table.

Round-by-round convergence
round	relocations	happy fraction	segregation index

Mild individual preference, strong city-wide effect: relocations fall to zero as the segregation index rises. That gap between what each agent wants and what the city becomes is Schelling's point.