Nine more states and the U.S. Virgin Islands have intercepted envelopes sent to government offices containing suspicious powder.
On Thursday, the letters arrived in Florida, Georgia, Kansas, New Mexico, North Dakota, South Carolina, Tennessee, Utah, and Wyoming.
Letters in several of the states led to office shutdowns or evacuations.
Tests indicate the powder found in Florida, Georgia, Kansas, North Dakota and Utah isn't harmful. Virgin Islands officials determined the powder there was corn starch.
Tests were pending in the other states.
Envelopes containing suspicious powder have already been received in a dozen other state capitals this week.
Officials in some of those states say the powder was flour, corn starch or some other harmless food substance.