One of the rectangular mounds at the Cahokia site is Mound 45, shown on the Patrick Map with its longer axis east-west. Mound 45 is located northwest of Mound 44 and directly west of Mound 40. McAdams shows Mound 45 as a 10 foot-high (3.05-meter) conical mound. Thomas, however, shows a 15-foot (4.6-meter) mound directly west, not northwest, of Mound 44, which may or may not represent Mound 45. The 1873 plat map (D Illustrated Encyclopedia and Atlas of Madison County, 1873) shows two large mounds in Section 34 which are probably Mounds 45 and 46. The Peterson McAdams Map shows an 8-foot (2.4 meter) mound in the area that is probably Mound 45.
There is no remnant of Mound 45 left today nor was there in 1966 when the UWM Map was made. The 1934 USGS map shows a building in the area where Mound 45 was located. The mound was probably destroyed between 1931 and 1966. Plotting its location from earlier maps onto the UWM Map indicates that the mound was in the northern one-third of the west side of a large borrow pit situated between Mound 44 and the railroad tracks. This borrow pit was excavated in advance of a planned interstate highway over the area of Tract 15A.
Examination of aerial photos provides no clue as to the location and condition of Mound 45. By 1933, when the Dache Reeves photos were made, all of Section 34 had been disturbed by construction of both a canal that straightened Cahokia Creek and a dog-racing track which probably intersected or cut into Mound 45. The photos do show an interesting soil disturbance east of the track, apparently where topsoil had been removed. There is no record of excavations in Mound 45.