In downtown Peoria, Illinois, this sign is trying to direct traffic on US 24 and Illinois route 29. Neither the US shield nor the Illinois square sign is shown. It's probably a city-made sign.
Just below that sign, you can also see the Illinois mileage markers used to indicate mileage on highways. Unlike Iowa's markers, the Illinois markers count mileage on a county-by-county basis. Often, they'll be installed at some convenient point, leading to situations such as the one shown at this location, with mileage reported to the hundredth mile.