Though no one knows the number of sundown towns in the United States, the largest estimate was that the nation had several thousand. The highest proportion of confirmed sundown towns are in the state of Illinois. It is difficult to confirm sunset towns because the towns did not keep, or do not want to show, official documents stating their status as sundown towns. For example, "One Hundred Years of Progress: The Centennial History of Anna, Illinois," although more than 400 pages long, never mentions Anna's 1909 expulsion of African Americans, the sundown signs at the northern and southern city limits in 1954, or anything else about race. 