A caucus of nine Illinois lawmakers, including the young Whig Party lawyer Abraham Lincoln, led the effort to have the capital moved to the Sangamon County village of Springfield. Their efforts were successful in 1837, when the Illinois General Assembly passed a law creating a two-year transition period and asking the state to move its capital to Springfield in 1839.
Workers built a state office building, large for the time, on the central square in Springfield in 1837-40. The cost was $240,000, of which the city of Springfield paid $50,000. The structure, constructed of locally-quarried yellow Sugar Creek limestone, contained chambers for both houses of the General Assembly, offices for the Governor of Illinois and other executive officials, and a chamber for the Illinois Supreme Court.
It was in this building that Lincoln served his final term as a state lawmaker in 1840-41. It was here, as a lawyer, that he pleaded cases before the state supreme court in 1841-60. It was here, in the Illinois House chamber, that he made Lincoln's House Divided Speech in June 1858. And it was to the same chamber, in May 1865, that his body was returned from Washington, D.C. prior to final burial in Springfield's Oak Ridge Cemetery.
As a result of economic growth spurred by the American Civil War and consequent industrialization, this fifth or Old State Capitol was, by the 1870s, too small to serve the purpose for which it had been built. Illinois built a sixth and final State Capitol building nearby in Springfield, and the state government turned the Old State Capitol over to Sangamon County to serve as the county courthouse.
In the early 1960s, the Civil War centennial rekindled interest in the historic central Springfield structure. In addition, Sangamon County's space needs had grown so urgent as to require the county to build for itself an entirely new courthouse building. The county retroceded the Old State Capitol to the state of Illinois, this time as a place of public assembly and museum of Lincoln history.
The state also dug out the plaza underneath and around the Old State Capitol and built extensive office space underneath it, which later served as the headquarters of the Illinois Historic Preservation Agency.
The reconstruction work was carried out in 1966-69, and the rebuilt House Chamber was available for the state's Constitutional Convention to use in 1970.
The restored Old State Capitol continues to be used for ceremonial functions. In February 2007 Illinois Senator Barack Obama officially announced his candidacy at this location for President of the United States, and in August 2008 he formally introduced his vice-presidential candidate, Joe Biden, with the building as a backdrop.