Author Miantae Metcalf McConnell provided documentation discovered during her research about Mary Fields to the United States Postal Service Archives Historian in 2006.

This enabled the USPS to establish Mary Fields' contribution as the first African-American female star route mail carrier in the United States.

After the American Civil War ended in 1865, she was emancipated and found work as a chambermaid on board the Robert E. Lee, a Mississippi River steamboat.

In 1884, Mother Amadeus was sent to Montana Territory to establish a school for Native American girls at St. Peter's Mission, west of Cascade.

[7] By 1895, at sixty years old, Fields secured a job as a Star Route Carrier which used a stagecoach to deliver mail in the unforgiving weather and rocky terrain of Montana, with the help of nearby Ursuline nuns, who relied on Mary for help at their mission.

She carried multiple firearms, most notably a .38 Smith & Wesson under her apron to protect herself and the mail from wolves, thieves and bandits, driving the route with horses and a mule named Moses.

These people, in accordance with the department's application process, posted bonds and sureties to substantiate their ability to finance the route.