This was the city in which Abraham Lincoln built his political career. Perhaps the Obama campaign was hoping that some of the redolent local symbolism would rub off?
The crowd was large, but not enormous. There were perhaps three to four thousand people, many of whom were wilting in the sweltering Illinois heat.
As Barack Obama took the stage his welcome was intense but this crowd did not seem to match the almost ecstatic welcome afforded him a year and a half ago when he stood in the same place on a freezing February day and announced he was running for president.
When Senator Joseph Biden made his appearance he bounded along the platform - maybe to show vigour.
He is, after all, 65, and a silver-haired veteran of American politics.
He is not the man many expected to be chosen by a campaign so focussed on youth. And the contrast was there for all to see - the young charismatic African-American with his arms round the shoulders of the older stalwart of the very white Washington establishment.