The incidents around the country are all similar in nature, with the perpetrator or perpetrators demanding money be put into Bitcoin.
Houston police confirmed that they are investigating at least five such threats.
Other agencies are investigating as well.
Up to a dozen emails were sent to businesses and schools in Washington, D.C.
Across the country, some schools were closed early and others were evacuated because of the threats. Penn State University notified students via a campus alert. Near Atlanta, people were ushered out of a courthouse.
The FBI also issued a statement:
"We are aware of the recent bomb threats made in cities around the country, and we remain in touch with our law enforcement partners to provide assistance. As always, we encourage the public to remain vigilant and to promptly report suspicious activities which could represent a threat to public safety."