HOW HAS THE TOTAL POPULATION OF ROCK ISLAND CHANGED OVER TIME?
- Annika OMelia
- May 23
- 5 min read
Updated: May 24
Annika O'Melia
In today's installment of Rock Island Facts, we explore how Rock Island's population has changed over time. Here are the facts broken down in two charts.
Rock Island, IL Population Data by Decade
Year | Population | % Change | Source |
1830 | 7,000 | ? | |
1850 | 1,711 | -76% | |
1860 | 5,130 | 200% | |
1870 | 7,890 | 54% | |
1880 | 11,659 | 48% | |
1890 | 13,634 | 17% | |
1900 | 19,493 | 43% | |
1910 | 24,335 | 25% | |
1920 | 35,177 | 45% | |
1930 | 37,953 | 8% | |
1940 | 42,775 | 13% | |
1950 | 48,710 | 14% | |
1960 | 51,863 | 6% | |
1970 | 50,166 | -3% | |
1980 | 47,036 | -6% | |
1990 | 39,684 | -16% | |
2000 | 36,716 | -7% | |
2010 | 39,116 | 7% | |
2015 | 39,064 | 0% | |
2020 | 37,366 | -4% | |
2025 | 35,540 | -5% |
The Stories Behind the Numbers
Before Rock Island was Rock Island
In the early 1800s, Saukenuk, located just south of present-day Rock Island, was one of the largest Native American villages in North America and home to Sauk and Meskwaki (Fox) people. The land that became Rock Island was the principal village of the Sauk people and the birthplace of Black Hawk, a renowned Sauk leader.
The village, situated strategically near the confluence of the Mississippi and Rock Rivers, had a population of between 4,000-7,000 people at its peak in the late 18th and early 19th centuries (Black Hawk State Historic Site).
In 1832, the Black Hawk War permanently changed the population of our area. United States forces, backed by militias and Native American allies, clashed with the Sauk and Meskwaki, pushing along the Rock River in a 15-week conflict that ended at the Battle of Bad Axe, leaving two-thirds of Black Hawk's followers dead (Wisconsin Historical Society).
Stephenson, IL (1835-1841)
By the time the land was officially platted as Stephenson on July 10, 1835, most of the Native population had been displaced (City of Rock Island).
The name was changed to Rock Island in 1841 to reflect its proximity to the actual Rock Island in the Mississippi River, which had been a significant military and trading post since the early 19th century.
Rock Island (1841-1900) A City Takes Root
Between 1841 and 1900, Rock Island's population grew steadily due to its pivotal role in transportation (rail & river), military manufacturing (the Arsenal), and industry. The arrival of immigrants and infrastructure development fueled the city’s transition from a frontier settlement to a significant urban center in the Midwest.
The Chicago and Rock Island Railroad reached the city in the early 1850's (Encyclopedia of Chicago).
In 1856, Rock Island became the site of the first railroad bridge across the Mississippi (Abraham Lincoln Historical Digitization Project).
The Rock Island Arsenal is established in the 1860's (Rock Island Arsenal History).
Immigrants from Germany, Ireland, and Scandinavia began settling in Rock Island, diversifying the population and labor force
In federal censuses before 1860, enslaved people were counted as 3/5 of a person for representation and taxation purposes under the U.S. Constitution's infamous Three-Fifths Compromise (National Archives).
Starting with the 1870 Census, formerly enslaved people were counted fully in the population as free citizens (U.S. Census Bureau).
Rock Island (1900-1960) A Booming Expansion
From 1900 to the 1960s, Rock Island, Illinois experienced a major population surge—growing from approximately 19,500 in 1900 to over 51,000 by 1960. This growth was fueled by a combination of industrial expansion, transportation infrastructure, military development, and immigration.
Rock Island became a manufacturing and industrial hub, with factories, foundries, and machine shops offering steady employment.
The city’s central location, strategic railroad junction and access to the Mississippi River made it ideal for river commerce and rail shipping.
The Rock Island Arsenal, a massive military weapons manufacturing facility, was one of the largest employers in the region (Rock Island Arsenal).
It grew rapidly during both World Wars, drawing thousands of workers—including many women and African Americans during wartime labor shortages.
Waves of European immigrants (Germans, Swedes, Irish, and others) settled in Rock Island in the early 1900s.
In the 1910s–1940s, African Americans from the South moved north during the Great Migration, seeking jobs and better lives.
The city invested in new schools, housing, and public works to support its growing population.
The rise of unions and organized labor also improved working-class stability, making Rock Island an appealing place to settle and raise a family.
Between 1900 and 1960, Rock Island’s population boomed because it was a Midwestern industrial powerhouse, a military production site, and a gateway for workers seeking opportunity. Its rivers, railroads, and factories powered not just local growth—but national contributions during major economic and wartime periods.
Rock Island (1970-2000) Population Decline
From its peak of 51,863 in 1960 to 36,716 in 2000, Rock Island lost over 15,000 residents in 40 years. This decline was shaped by the loss of manufacturing jobs, federal downsizing, suburban flight, and aging infrastructure—trends that mirrored those seen across the Rust Belt (Brookings Institution).
Automation, globalization, and outsourcing impacted local industry, including:
International Harvester - Farmall Works closing in 1985
Chicago, Rock Island & Pacific Railroad - closing 1980
Eagle Food Centers - closing 2003
The Arsenal experienced postwar budget cuts.
Suburban migration reduced the city’s tax base and strained public services.
Infrastructure aged as new development favored surrounding areas.
Birth rates dropped and the population aged (US Census Data).
Rock Island (2000 to Present) Gradual Decline
Between 2000 and 2025, Rock Island experienced a gradual population decline, reflecting broader regional and national trends affecting many Midwestern cities (World Population Review). Rock Island continues to feel the effects of decreasing manufacturing jobs over the past 50 years as well as limited diversification in the local economy. Residents must often look elsewhere for upward mobility and to access diverse job markets. Suburbanization continues to impact Rock Island as residents relocate to regions with newer housing and more amenities. An aging population and lower birth rates nationally also impact the population base. Rock Island experiences an outflux of young people graduating from High School, secondary school and trades who seek more and better opportunities in other places.
Rock Island Moving Forward
We can't know for certain how the population of Rock Island will change moving forward, but hopefully, Rock Island Line will be here to bring you the facts as they unfold.
Sources
Population sources are listed in the table data if you select the link.
Article sources are linked to highlighted text throughout the article.
Photo Sources:
Black Hawk: https://www.blackhawkpark.org/museum.php
Fort Armstrong: https://commons.wikimedia.org/wiki/File:Fort_Armstrong,_Rock_Island.jpg
Rock Island Packet: https://digital.library.wisc.edu/1711.dl/JLX65X7WX3HZ58S
1869 Bird's Eye View: https://www.loc.gov/resource/g4104r.pm001830
Downtown and Park photos: Rock Island Preservation Society and City of Rock Island Photo Gallery
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