Oregon State Police officials say they don't know of any suspicious packages found following the threats, and the State Police bomb squad did not respond.
The calls began about 2:30 p.m. and continued for an hour. Police say some of the courthouses were evacuated. A Salem office building housing the State Police headquarters also received a threat and was evacuated.
This is the third time in less than three weeks that a state has been inundated with bomb threats. On Nov. 2, nine courthouses in Nebraska received bomb threats within an hour of each other.
Just like Washington's threats, the caller in the Nebraska cases told court clerks there were bombs in the courthouse set to go off.