when was it explored first?
During the 18th and early 19th centuries,
Colorado River
During the 18th and early 19th centuries, 
directions to i-70 east from my current location Transcontinental Interstate Highway in the United States, when was it opened for public? October 14, 1992. is it located on the banks of any river? Yes Colorado river how long is it? It stretches' from Cove Fort, Utah, to Baltimore, Maryland which main tributaries does it have? It is joined by over 25 significant tributaries, of which the Green River is the largest by both length and discharge. what type of people can be seen here? Paleo-Indians of the Clovis and Folsom cultures, who first arrived on the Colorado Plateau about 12,000 years ago
wiki:13581146
Colorado River [SEP] Early explorers
Kino's 1701 map, "Paso por Tierra a la California," is the first known map to label the river as the Colorado. During the 18th and early 19th centuries, many Americans and Spanish believed in the existence of the Buenaventura River, purported to run from the Rocky Mountains in Utah or Colorado to the Pacific Ocean. The name "Buenaventura" was given to the Green River by Silvestre Vélez de Escalante as early as 1776, but Escalante did not know that the Green drained to the Colorado. Many later maps showed the headwaters of the Green and Colorado rivers connecting with the Sevier River (Rio San Ysabel) and Utah Lake (Lake Timpanogos) before flowing west through the Sierra Nevada into California.