In the previous week, truck arrivals had also dropped by 6%.
It is the third consecutive drop since truck arrivals returned to normal during June 29-July 5 for the first time since Covid-19 struck earlier this year.
Overall volumes during the week of July 20-26 were down 89% for those crossing via land, and 95% through airports compared to the same time a year ago.
Canada and the U.S. have agreed to keep the border closed to all non-essential travel until Aug. 21 to slow the spread of Covid-19.
The restrictions, first introduced in late March, are not applicable to commercial vehicles.