The traditional subgenera of Colon Herbst containing the North American fauna are Colon s.str., Myloechus Latreille, and Eurycolon Ganglbauer. We use these and also describe Tricolon and Striatocolon as new subgenera. Identification of species in the genus Colon is taxonomically difficult because of allometric variation of external characters in males, and lack of distinctive characters in females. We present keys, illustrations, and descriptions to distinguish the known North American species. A total of 37 species names have been previously applied to Colon in North America. We designate lectotypes for Colon thoracicum Horn, C. asperatum Horn, C. oblongum Blatchley, C. dentatum LeConte, C. pusillum LeConte, C. putum Horn, C. hubbardi Horn, C. nevadense Horn, and C. liebecki Wickham. We recognize 16 names as synonyms of previously named species as follows: C. clavatum Mannerheim = C. bidentatum Sahlberg; C. complicatum Hatch = C. celatum Horn; C. decore Casey = C. thoracicum Horn; C. excisum Hatch = C. hubbardi Horn; C. femorale Hatch = C. lanceolatum Hatch; C. kincaidi Hatch = C. hubbardi Horn; C. mannerheimi Szymczakowski = C. oblongum Blatchley; C. pusillum Horn = C. dentatum LeConte; C. putum Horn = C. dentatum LeConte; C. paradoxum Horn = C. bidentatum Sahlberg; C. nevadense Horn = C. celatum Horn; C. productum Hatch = C. hubbardi Horn; C. rufum Hatch = C. dentatum LeConte; C. schuhi Hatch = C. discretum Hatch; C. serripoides Hatch = C. asperatum Horn; C. pribilof Hatch = C. liebecki Wickham. We describe 22 species as new, as follows. In the subgenus Tricolon: C. blatchleyi and C. pacificum. In the subgenus Colon: C. arcum, C. nitidum, C. politum, and C. vancouverensis. In the subgenus Myloechus: C. boreale, C. californicum, C. chihuahua, C. chiricahua, C. grossum, C. hatchi, C. hesperium, C. incisum, C. longitorsum, C. megasetosum, C. mesum, C. monstrosum, C. pararectum, C. potosi, C. similare, and C. xilitla. All these species are restricted to North America except for C. bidentatum and C. politum which are northern Holarctic. This yields 42 species recognized for the North American fauna. These beetles occur in forest, open woodland, and grassland habitats. Their larvae, biology, and food are still unknown.