Police say a threat against the courthouse was phone in at 12:12 p.m. But after a thorough search of the building nothing was found.
The courthouse, along with nearby businesses in the 800 block of North King Street, were evacuated.
The courthouse re-opened before 4 p.m.
King Street was closed from 8th Street to 4th Street, but it has also reopened.
The New Castle County courthouse was the scene of a shooting earlier this month that left two women dead.