根据CNN,从陆路加拿大和墨西哥回美国的已打疫苗公民不需要提供Covid 测试
Is testing required?
Fully vaccinated air travelers are still required to test negative for Covid-19 within three days of their flight's departure for the United States, in line with the current testing rule.
As mentioned above, unvaccinated American citizens will be required to take a Covid-19 test within one of day of their departing flight and again after arrival.
There is no testing requirement at land borders.