The Inka Road stretches over 24,000 miles through six modern-day countries: Colombia, Ecuador, Peru, Bolivia, Argentina, and Chile. It stands among the great feats of engineering in world history, serving as a network that linked Cusco (in modern-day Peru) with the far reaches of the Inka empire. The Inka road ranges over mountains, tropical lowlands, rivers and deserts and is still crucial in uniting contemporary Andean communities.

The Rumi Colca gateway, Cusco, Peru. Photo by Doug McMains, 2014.

On Friday, June 26, the National Museum of the American Indian in Washington, DC, will open the exhibition "The Great Inka Road: Engineering an Empire," which will tell the historical and cultural story of the Inka Road from its beginnings in early Andean cultures to its significance to the Inka Empire and its use in the modern era. The experience features over 140 objects, the oldest being a ceramic Chavín stirrup spout bottle dating from ca. 800–100 B.C., numerous videos and a wealth of photography.

(Editor's note: Some readers have asked—why "Inka"? Isn't it spelled "Inca"? Although "Inca" is traditional and more prevalent, the use of "Inka" is gaining acceptance as a more accurate transliteration, as the National Geographic Style Guide notes. The NMAI scholars who organized this exhibit and wrote the accompanying book have chosen to use the new spelling, and in this case we're following their lead.)

Agricultural terraces on a steep hillside. Colca Canyon, Peru, 2014. Photo by Doug McMains, National Museum of the American Indian, Smithsonian Institution.

The pictures and information are collected in the book The Great Inka Road: Engineering an Empire, edited by Ramiro Matos Mendieta (Quechua) and José Barreiro (Taíno), available at the NMAI store.

Modern Andean highways. Near Q’eswachaka, Canas Province, Peru, 2014. Photo by Doug McMains, National Museum of the American Indian, Smithsonian Institution.

A llama caravan travels the Inka Road. Warautambo, Peru, 1990. Photo by Ramiro Matos Mendieta, National Museum of the American Indian, Smithsonian Institution.

The upper Amazon, near Loromayo, Peru, 2014. Photo by Doug McMains, National Museum of the American Indian, Smithsonian Institution

Terraces have allowed the Inka and their descendants to transform steep terrain into viable agricultural land. Pisac, Peru, 2014. Photo by Doug McMains, National Museum of the American Indian, Smithsonian Institution.

The coastal desert of Peru, with the Andean highlands visible in the distance. Near Camana, Peru, 2014. Photo by Doug McMains, National Museum of the American Indian, Smithsonian Institution

Families walk from the center of Cusco toward the temple site at Sacsayhuaman to celebrate Inti Raymi, the Inka Festival of the Sun. Cusco, Peru; June 2014. Photo by Doug McMains, NMAI.

An Inka road with sidewalls cuts through an agricultural valley. Colca Canyon, Peru, 2014. Photo by Doug McMains, National Museum of the American Indian, Smithsonian Institution.

Trailside water fountain, Machu Picchu, Peru (Wright Water Engineers, Inc., 1998)

Portion of the east flank trail at Machu Picchu, Peru (Wright Water Engineers, Inc., 1998)

The Inka Road through the desert. Jujuy Province near the Bolivian border, Argentina. Photo by Megan Son and Laurent Granier, 2006.

Q'eswachaka, Apurimac River, Canas Province, Cusco, Peru. Photo by Doug McMains, 2014.

A woman travels the Inka Road on the shores of Lake Titicaca near Pomata, Peru. Photo by Megan Son and Laurent Granier, 2006.

Two men walk the Inka Road, Charazani, Bolivia. Photo by Ramiro Matos, 2011.

Walking the Qhapaq Ñan Jujuy, Argentina Photo by Axel E. Nielsen, 2005

Inka road in the upper Amazon, Quijos River Valley, Ecuador. Photo by Jorge Arellano, 2001.

The Qhapaq Nan in Contisuyu, Colca Canyon, Peru. Photo by Doug McMains, 2014.

The Rumi Colca gateway, Cusco, Peru. Photo by Doug McMains, 2014.

The Inka Road skirting Lake Junin, just south of Pumpu, a large Inka administrative center. Lake Junin, Peru. Photo by Megan Son and Laurent Granier, 2006.

The Great Inka Road
The Qhapaq Ñan, or Road of the Inka, made this triumph possible. A vast complex of roads, bridges, and other structures, the Qhapaq Ñan was the largest construction in the Western Hemisphere when Inka power was at its height. The Inka state used the road system strategically to oversee diverse populations within an empire of 2 million square kilometers (772,000 square miles), the equivalent of California, Nevada, Arizona, New Mexico, and Texas combined.
http://americanindian.si.edu/inkaroad/