The city's main post office, home of the mail processing and distribution center, was tested for anthrax on Saturday as part of a nationwide precautionary program.
The local distribution center, 3135 First Ave. N, is one of 200 postal facilities around the country included in the program, according to the Postal Service. The Tampa International Airport post office was tested last week.
"This is strictly a precautionary measure. There is no reason to believe that anthrax is present in this plant and for anyone to be concerned," John Hoyle, manager of the St. Petersburg Processing & Distribution Center, said in a statement.
The samples will be analyzed at a Centers for Disease Control laboratory, with results expected in four or five days.