Authorities searched two planes in Atlanta, but no bombs were found, officials said on Saturday.
"The all-clear has been given and no devices were discovered on board either aircraft. Normal airport operations have resumed," airport officials said in an email to reporters.
Earlier, officials said they had received a credible bomb threat, leading to military jets escorting two flights to Atlanta. Both landed safely at Hartsfield-Jackson Atlanta International Airport in the late afternoon.
The flights were identified as Delta 1156, from Portland, Ore., and Southwest 2492, from Milwaukee.
TV images showed passengers leaving the planes as emergency personnel and bomb-sniffing dogs conducted their search.