Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
[cite:742038]
most helpful reference in terms of nomenclature, stats, and zoogeography; collaborative effort (each section coordinated/compiled by a leading expert)
NB: work in progress, so use the stats with caution (watch for the 'Complete' remark at the family entry)

NOTE: as of this date, the link no longer works
https://insects.tamu.edu/research/collection/hallan/test/Arthropoda/Insects/Coleoptera/Family/Coleoptera1.htm