Sangamon County, IL

Settlement & growth (pre-1960)

Before European settlement, the area now known as Sangamon County was inhabited by the Kickapoo and Potawatomi peoples, who used the Sangamon River as a travel and trade corridor. French explorers and traders passed through in the 17th and 18th centuries, but no permanent European settlement occurred until after the War of 1812. The 1818 Treaty of Edwardsville forced the Kickapoo to cede most of central Illinois, opening the land to American settlers.

The first major wave of American settlers arrived in the 1820s and 1830s, primarily from Kentucky, Tennessee, and the Ohio River Valley. These were largely of Scots-Irish and English stock, drawn by the promise of cheap, fertile prairie land under the 1820 Land Act. They founded the county’s earliest towns: Springfield (chosen as the county seat in 1821), Rochester (settled 1823), and Petersburg (1832). Abraham Lincoln himself arrived in 1837, practicing law in Springfield and later launching his political career from the county. By 1850, the county’s population had reached 19,000, overwhelmingly native-born and Protestant.

A second wave came with German and Irish immigration between 1840 and 1880. Germans, many fleeing political unrest and economic hardship, settled in Springfield’s north side and in the farming communities of Chatham and Pleasant Plains. They established Lutheran churches, breweries, and German-language newspapers. Irish immigrants, arriving during and after the Great Famine, concentrated in Springfield’s “Irish Patch” near the railroad yards and worked on the construction of the Alton & Sangamon Railroad. By 1880, foreign-born residents made up about 15% of the county’s population.

The post-Civil War era saw the arrival of African Americans, initially as freedmen moving from the Upper South. By 1900, Springfield’s Black population had grown to about 2,000, concentrated in the city’s east side. The Great Migration (1910–1940) brought a much larger wave of Black families from Mississippi, Arkansas, and Tennessee, seeking industrial jobs in Springfield’s coal mines, railroad shops, and the state government. The 1908 Springfield Race Riot, a violent white mob attack on Black residents, temporarily slowed this migration but did not stop it. By 1950, Black residents made up 8.5% of the county’s population, with the largest enclave in the East Springfield neighborhood.

European immigration slowed sharply after the 1924 Johnson-Reed Act. The county’s growth from 1920 to 1960 was driven by natural increase and domestic migration from rural Illinois. The state capital’s expanding bureaucracy, along with the growth of Memorial Medical Center and the University of Illinois Springfield (founded 1969), attracted a steady stream of white-collar workers from across the Midwest. The county’s population peaked at 201,000 in 1960.

Modern era (post-1965)

The 1965 Hart-Cellar Act had a muted effect on Sangamon County compared to coastal or Sun Belt regions. The foreign-born share remained below 2% through 2020, and the county did not experience the large-scale immigration from Asia, Latin America, or Africa seen in Chicago or the suburbs of Cook County. However, modest shifts did occur.

Hispanic population growth began in the 1990s, driven by Mexican immigrants working in agriculture and food processing. The town of Riverton and the unincorporated area of Clear Lake saw small clusters of Hispanic families, and by 2020, the county’s Hispanic share reached 2.8%. East/Southeast Asian residents, primarily of Vietnamese and Filipino origin, arrived in the 1980s and 1990s, many as healthcare professionals or refugees resettled by Catholic Charities. They concentrated in Springfield’s west side near the hospitals. The Indian subcontinent community, numbering about 1,700, grew after 2000, largely composed of doctors and engineers working at Memorial Medical Center and the Illinois Department of Public Health.

Domestic migration patterns shifted after 1970. The county lost population from 1970 to 1990 as manufacturing declined and young adults left for Chicago or the Sun Belt. Suburbanization reshaped the county: Sherman and Williamsville grew as bedroom communities for Springfield commuters, while Leland Grove and Jerome became affluent enclaves. The Black population, which had been concentrated in East Springfield, began dispersing to the south and west sides of Springfield and to the village of Grandview after fair-housing reforms in the 1970s. By 2020, the Black share had risen to 12.5%, but the county remained one of the least diverse in Illinois outside of Chicago.