Which 1869 expedition led by John Wesley Powell first explored the Colorado River through the Grand Canyon?

The 1869 expedition led by John Wesley Powell through the Grand Canyon was the Powell Geographic Expedition.

Powell organized the journey to explore the largely unmapped Colorado River and its canyon system. The expedition began at Green River Station in Wyoming Territory on May 24, 1869, with nine men and four wooden boats. The party traveled downstream through the Green and Colorado rivers, passing through difficult rapids and deep canyon country.

Powell and his companions reached the Virgin River in present-day Nevada on August 30, 1869. Several members had left earlier, and three men abandoned the expedition before its final stages. Despite the hardships, the journey supplied important geographic information about the canyon region.

The expedition is often described casually as the first trip through the Grand Canyon, although earlier Indigenous travelers knew and used the region, and some miners had entered portions of the canyon. Powell later led a second Colorado River expedition in 1871–1872, which produced more systematic scientific observations and maps.