Roughly 95% of all Americans are under lockdown, as 42 states issue stay-at-home orders.

Please note that it is the STATES issuing the lockdowns, NOT the federal government.

Source:

• 
  December 24, 2020. Susie Neilson and Aylin Woodward. “A Comprehensive Timeline of the Coronavirus Pandemic at 1 Year, from China’s First Case to the Present.” Business Insider.
  https://www.businessinsider.com/coronavirus-pandemic-timeline-history-major-events-2020-3.
  Magazine.