She was the designer of many landmark buildings and spaces for the Fred Harvey Company and the Santa Fe Railroad, notably in Grand Canyon National Park.

[citation needed] When the Indian community was ravaged by a smallpox outbreak, Colter's mother tried to burn all of the Native American things they had for fear that it would get her family sick.

[10][11] The Indian Buildings, one of Minnie's ideas executed by her husband, were meant to entertain passengers as trains made stops to replenish water and fuel.

[11] As one of the country's few female architects – and arguably the most outstanding – Colter worked in often rugged conditions to complete 21 landmark hotels, commercial lodges, and public spaces for the Fred Harvey Company, by then being run by the founder's sons.Fred Harvey developed the West along the Santa Fe's main route through strategic use of restaurant efficiency, clean-cut and pretty young women, high-end tourism, and quality souvenirs.

Its striking blend of Pueblo people and Spanish artistic influences, today known locally as the Santa Fe Style, became very popular across the region.

[13] Colter created a series of remarkable works in the Grand Canyon National Park, mostly on the South Rim: the 1905 Hopi House,[14] the 1914 Hermit's Rest and observatory Lookout Studio, and the 1932 Desert View Watchtower, a 70-foot-tall (21 m) rock tower with a hidden steel structure, as well as the 1935 Bright Angel Lodge complex, and the 1922 Phantom Ranch buildings at the bottom of the canyon.

Considering the Phantom Ranch's location, Colter's use of on-site fieldstone and rough-hewn wood was deemed the only practical thing for the permanent buildings that replaced tents.

[3] Colter's pioneering masterwork may have been the 1923 El Navajo in Gallup, New Mexico, remarkable for its forward-looking fusion of a Native American-inspired design on the severe Art Deco building by Santa Fe Railway architect A. E. Harrison.

The sprawling, hacienda-style Spanish Colonial Revival building[21] in Winslow, Arizona, has been called "the last great railroad hotel built in America".

[22] Closed in 1957, in a long decline it was first a drab 1960s office building for the Santa Fe, and then was empty when the National Trust for Historic Preservation placed the hotel on its annual "Most Endangered" list.

[23] Allen Affeldt heard about the endangered masterpiece, and in 1996 he and his wife Tina Mion, an artist, purchased it, and soon reopened parts of the hotel for business.

The compound and gardens, being restored to the original and intended grandeur, are the core elements of the La Posada Historic District on the National Register.

Under a spectacular arched ceiling, a dazzling floor appears to be random zigzags and geometrics; from another angle the pattern turns out to be a block-long Navajo blanket made of linoleum tiles.

The fabulous dining room and her sleek, Streamline Moderne cocktail lounge were padlocked except for occasional movie shoots and Los Angeles Conservancy tours until 2018.

During the Depression, a 1922 inn had been overhauled by Civilian Conservation Corps workers to the Mission Revival style, using local materials and Native American motifs.

Then Colter supervised the refreshening, provided a new color scheme, and commissioned Hopi artist Fred Kabotie to put murals in the dining areas.

Showing that she was unafraid of the modern when the situation called for it, Colter installed plate glass windows to open up views of the splendid scenery.

[27] Colter was the creator of Mimbreño china and flatware for the glamorous Super Chief Chicago–Los Angeles rail service, begun in 1936 by the Santa Fe Railroad.

[28] Colter, herself by then an Indian art expert, based her designs on 1100 CE Mimbres patterns excavated by her friends Harriet and Cornelius Cosgrove at the Swarts Ruin in New Mexico from 1924 to 1927.