She taught junior high school for 15 years in Lexington, Massachusetts, spending her summers on vigorous walking tours, which she called vagabonding throughout the United States, Mexico, Canada, and Europe.

On 7 May 1947, Secretary of War Robert P. Patterson promoted Hallaren to full colonel and appointed her the third director of the WAC.

She was inducted into the National Women's Hall of Fame in Seneca Falls, New York, in 1996 and was featured by Tom Brokaw in his book The Greatest Generation.

She died at the Arleigh Burke Pavilion, an assisted living facility for retired military personnel in McLean, Virginia.

[4] This article incorporates public domain material from websites or documents of the United States Army Center of Military History.