Upvote:5
If any of you is a US citizen, that person needs no record of entry.
For foreigners, the entry should be electronically recorded and searcable on the I-94 Website. Thus, an entry stamp isn't really needed in practice these days, but if a foreigner doesn't get one, carrying a printout of the result page of the linked search, along with your passport, is a good idea in case you're stopped by the police, Immigration Enforcement or Border Patrol.