America’s First Archaeological Reserve

Arizona’s Casa Grande National Monument preserves the remains of structures built by the Hohokam people in the 1300s. In the Gila River Valley these ancient people built over 1,000 miles of  irrigation canals, successfully growing corn, beans, squash, cotton and tobacco. Today several Native American tribes believe they have ancestral links to the Hohokam. The O’odham people of Southern Arizona still use the ruins for ceremonials and special events.

Spanish missionary, Father Kino, rode through the valley in 1694 and refered to the deserted structure as Casa Grande, or Great House, in his records. The site became the nation’s first archeological reserve in 1892 – the fifth oldest unit in the National Park system. Casa Grande was designated a National Monument in 1918.

We watch a 15-minute film and browse the compact but informative museum relating background on the Hohokam people and Casa Grande before taking the short walk out to the ruins. The largest structure – four stories and 11 rooms – has a metal roof protecting the ancient walls from weather damage. Signs along the self-guided path relate informative details.

Unlike most of the ruins we see in the Southwest Casa Grande was not built with stone or adobe bricks. Caliche is a concrete-like hardpan found several feet below the surface in this region. The Hohokam mixed ground-up calice wth water to procude a sticky mud for building walls, sealing roofs and plastering walls.

No one knows why the unusual structure was built or how it was used – center of government, education, religion or trade are speculations. I’m fascinated with how architectual details signify astronomical occurances. A small circular window in the west wall aligns with the setting sun on the summer solstice. A square hole in an upper wall aligns once every 18.5 years with the setting moon at an extreme point in its cycle. Additional windows and doorways align with the sun or moon at significant times of the year. Was this an observatory? We believe the Hohokam devised a calendar based on the motions of the sun and moon and incorportated that calendar into their architecture. Did it relate to their crops and farming?

Casa Grande was part of a much larger community. Excavated walls and unearthed mounds indicate several compounds comprised of houses, work areas, courtyards and storage rooms. In the center of the compound an oval ballcourt was used for community activities.

We don’t know the reasons Casa Grande was abandoned – disease, drought, flood, social or political issues. By 1450 the Hohokam culture, that had lasted 1,000 years, had come to an end. Today agriculture is still key to the region; irrigated fields support Arizona’s cotton industry. Standing in the shadow of the ancient walls and gazing across wind-blown fields one is almost transported into a world as the Hohokam knew it.

When You Go: Casa Grande National Monument is open 8am-5pm every day of the year except Thanksgiving and Christmas. The monument is located in Coolidge, Arizona about an hour’s drive from both Phoenix and Tucson.