According to the United States Geological Survey, the quake was recorded at 2:51 a.m.at Three Lakes, Wash., in Snohomish County.
Residents of Vancouver, Victoria and other spots near the border jumped on Twitter in the middle of the night to say they felt shaking.
"Indeed it was not a very big natural disaster, but it was large enough that shaking could be felt in the Greater Vancouver area".
However, he said this quake serves as a reminder that Metro Vancouverites live in a seismic activity zone, and to be prepared for a major emergency.
This was the largest quake in the Pacific Northwest since February 28, 2001, when a 6.8 magnitude struck near Olympia and caused widespread damage.
A second quake, measured at magnitude 3.5, was reported near Monroe a few minutes afterward.
Further south along the Pacific coast, a magnitude 4.9 aftershock of last week's Southern California earthquakes was felt widely in the region on Friday morning. There were no immediate reports of damage or injuries. There have been thousands of aftershocks of the magnitude 6.4 natural disaster on July 4 and the 7.1 quake that occurred the next day.