For U.S. Labor Day. Ends today (apologies for the short notice), presumably 11:59p.m. Mountain Time, which I think is 6:59a.m. BST tomorrow, Wednesday 3rd.
IntroductionUS CensusCanadian CensusThe US census collection includes federal census records as well as some state and county census records and special census records. The Canadian collection includes national census records as well as some more specialised or location-specific census records. It says it has millions of additions since last year. Some of this may be free elsewhere at all times, so check before spending too much time on a particular set.
You need an account (free) but don't have to sign up for a free trial of the whole site. No payment details are taken on registration.
As always with free periods, save anything you find on your own device, as you'll need a sub to see it after the offer closes.