For a time over the past years US citizens were not allowed to visit Canada - the changes due to Covid were significant and rules were established that prevented non-essential travel across the northern border. This affected leisure travel as well as commercial traffic related to commodities (including lumber).
Many countries eased restrictions earlier this year, and a quick review of current guidelines show that travel to Canada is once again possible for US citizens, the caveat being you should be fully vaccinated to avoid any additional requirements including quarantine for 14 days and isolation for 10 days.
Any travelers also need to create an ArriveCAN account to provide proof of vaccination and travel plans.
More information on current expectations can be found here.