Pre-America's Biggest City

Per Square Mile recount the history of Cahokia, a Mississipian settlement that was the biggest city in America from about 1250 to 1800.

1 minute read

February 11, 2011, 9:00 AM PST

By Nate Berg


"The city's inhabitants built over 100 mounds, eighty of which remain. One of them still towers 92 feet over the surrounding fields and is easily visible from the scratched postage-stamp windows of St. Louis' Gateway Arch. With somewhere between 10,000 to 15,000 people, it held the record for the largest American city until around 1800, when Philadelphia finally overtook it.

With that many people crammed into just under three-quarters of a square mile-the estimated size of the city's neighborhoods-it may sound like Cahokia was as cramped as the slums of Upton Sinclair's Chicago. But it probably didn't feel that way. Sweeping plazas and towering mounds added nearly three square miles of open space, keeping much of the city open and airy like Baron Haussmann's Paris. Yet unlike the city on the Seine's astronomical modern density of 58,890 people per square mile, Cahokia's population lived at a positively suburban 1,000 to 1,500 people per square mile, thanks to the plazas and mounds."

Based on archaeological excavations, just 20% of the city's land was dedicated to housing.

Tuesday, February 8, 2011 in Per Square Mile

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Get top-rated, practical training

Aerial view of single-family homes with swimming pools in San Diego, California.

San Diego to Rescind Multi-Unit ADU Rule

The city wants to close a loophole that allowed developers to build apartment buildings on single-family lots as ADUs.

March 9, 2025 - Axios

Canadian flag in foreground with blurred Canadian Parliament building in background in Ottawa, Ontario, Canada.

Has President Trump Met His Match?

Doug Ford, the no-nonsense premier of Canada's most populous province, Ontario, is taking on Trump where it hurts — making American energy more expensive.

March 11, 2025 - Toronto Star

Close-up of green ULEZ sign in London, UK.

Study: London ULEZ Rapidly Cleaning up Air Pollution

Expanding the city’s ultra low-emission zone has resulted in dramatic drops in particle emissions in inner and outer London.

March 10, 2025 - Smart Cities World

Tents set up by unhoused people under freeway overpass in San Jose, California with American flag above them.

San Jose Mayor Takes Dual Approach to Unsheltered Homeless Population

In a commentary published in The Mercury News, Mayor Matt Mahan describes a shelter and law enforcement approach to ending targeted homeless encampments within Northern California's largest city.

March 14 - The Mercury News

Blue Atlanta streetcar on street in downtown Atlanta, Georgia.

Atlanta Changes Beltline Rail Plan

City officials say they are committed to building rail connections, but are nixing a prior plan to extend the streetcar network.

March 14 - Saporta Report

New York City city hall building.

Are Black Mayors Being Pushed Out of Office?

The mayors of New York, St. Louis, and Pittsburgh all stand to lose their seats in the coming weeks. They also all happen to be Black.

March 14 - Governing

Urban Design for Planners 1: Software Tools

This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.

Planning for Universal Design

Learn the tools for implementing Universal Design in planning regulations.