Nancy Writebol, 59, arrived in the United States after being flown overnight from Liberia and will be treated by infectious disease specialists at Emory University Hospital, according to Christian missionary group SIM USA.
She will be in the same isolation ward as Kent Brantly, 33, an Ebola-infected American doctor who was able to walk into the hospital when he arrived by ambulance on Saturday.
The pair are believed to be the first Ebola patients ever treated in the United States, and health officials have said the virus does not pose a significant threat to the public.
The medical aircraft carrying Writebol made a brief stop Tuesday morning to refuel in Bangor, Maine, before landing at Dobbins Air Reserve Base in Georgia, local television footage showed.
She arrived at Emory's hospital by ambulance just before 1 p.m. EST. The two paramedics who transported her into the hospital also wore white, full-body hazard suits to avoid any direct contact with the patient.
The contagious disease, concentrated in Africa, has killed nearly 900 people since February and has no proven cure. The death rate in the current epidemic is about 60 percent, experts say.
Writebol and Brantly served on a joint team in Monrovia run by Christian aid groups SIM USA and Samaritan's Purse. They returned to the United States separately because the plane equipped to transport them could carry only one patient at a time.
Writebol, a mother of two from Charlotte, North Carolina, is a longtime missionary who had been working for SIM USA as a hygienist who decontaminated protective suits worn by healthcare workers inside an isolation unit at a Monrovia treatment center.
The relief groups have said the condition of each aid worker improved in Liberia after the pair received an experimental drug previously tested only on monkeys.
It was not clear whether they will receive more of the drug in the United States. A spokeswoman for Samaritan's Purse had no update on Brantly, who she said wanted to keep the latest details of his condition and treatment private.
Writebol's arrival in Atlanta came a day after Mount Sinai Hospital in New York City said it was testing a man who traveled to a West African nation where Ebola has been reported. He arrived at the emergency room on Monday with a high fever and a stomach ache but was in good condition, hospital officials said.
The New York City Health Department, after consulting with the hospital and the U.S. Centers for Disease Control and Prevention, said the patient was unlikely to have Ebola.
Health officials near Columbus, Ohio, also reported that a female patient recently returned from abroad had been checked for Ebola, with tests coming back negative. Franklin County, Ohio, Health Commissioner Susan Tilgner said a hospital had tested the woman to rule out Ebola due to risk factors, which she declined to describe in detail.
She said the tests had taken a few days and declined to say what country the woman had traveled to.