The term 'Oregon or Santa Fe' can be summarized by the crossword solution 'TRAIL'. This term refers to the Oregon TRAIL and the Santa Fe TRAIL, two of the most important trails in American history. The Oregon TRAIL was a 2, 170-mile route that connected Missouri to Oregon and was used by settlers to travel westward in the mid-1800s. The Santa Fe TRAIL was a 900-mile route that connected Missouri to New Mexico and was used by traders to transport goods between the two regions. Both trails played an important role in the development of the United States.