Relying on the same source (named below) here is the information on Summum, mistakenly thought to have had the name changed to Douglas: Summum (Fulton Co.) PO est. 4/13/1836; dis. (disbanded) 4/28/1847; reest. 10/9/1851/ dis. 5/29/1852; reest. 4/25/1856; active. Formerly Oberlin. Pop. (Rand McNally Geographical and Commercial Atlas, [Chicago 1958] ) 225. [Note: there is only one location named Summum in the List of Illinois Place Names, and it is located in Fulton Co., not Knox Co.] Douglas (Knox Co.) PO est. (ch. from Douglass) ca. 12/31/1878; dis. since 1931; now RFD Yates City. CB&Q. Formerly Douglass, Summit Pop. (Rand McNally Geographical and Commercial Atlas, [Chicago 1958] ) 100. Illinois Libraries, Vol. 50, No, 4 Springfield, Illinois April-May-June 1968 "A List of Illinois Place Names." [So far as I know this is "The Authority" on Illinois place names. From my own experience I know that there are omissions which (probably) are mostly small groups of houses which were never incorporated, never had a post office, and never had railroad service.] ~ ~ ~ ~ ~ ~ Summit Summit (Champaign Co.) Now Philo (Bateman & Selby's Historical Encyclopedia of Illinois for various counties 823). Summit (Cook Co.) PO est. 2/5/1841; dis. (disbanded) 9/5/1848; reest. 12/7/1848; dis. 5/17/1849; reest. 9/16/1853; dis. 8/18/1855; reest. 11/25/1859; dis. since 1931; includes Argo, the combined municipality being incorporated as Summit but PO Argo. Incorporated as a village 6/20/1890. (Railroad) GM&O Pop. (1960) 10, 374. Summit (township) (Effingham Co.) Summit (Knox Co.) Now Douglas Summit (Macon Co.) Now Harristown Summit (Moultrie Co.) Now Gays Summit (St. Clair Co.) Listed in Rand McNally Geographical and Commercial Atlas (Chicago 1956) but not in the 1958 edition. RFD East St. Louis. (Railroad) L&N. Summit (Tazewell Co.) RFD Mackinaw. (Railroad ) IT. Listed also are the following: Summit Grove, Summit Heights, Summit Hill, Summit Park, Summit Prairie, and Summit View.