Jefferson County is a county in Oregon. It lies on the eastern side of the Cascade Mountains, with its terrain stretching from the peaks of the Cascades, through the Deschutes River valley, and on to the high desert of Eastern Oregon. It has an area of about 1800 square miles (making it about 50% bigger than Rhode Island), and has a population of around 25,000 people. By the standards of Eastern Oregon, this is small and heavily populated.
Most of the population of Jefferson County lives in the county seat, Madras, or in the adjoining towns. Two major highways cross through Jefferson County: the north-south US Highway 97 and the east-west US Highway 26, with Madras at the center of these roads. Much of the rest of the county is sparsely populated, with both the areas in the Cascade Range and the high desert lacking any towns. In recent decades, the area has grown in population as Bend, Oregon has become a major resort and tourist city, with Jefferson County growing in population as people have come to experience the beautiful scenery.
Jefferson County is also home, in part, to the Warm Springs Indian Reservation, and has the highest percentage of Native American residents of any of Oregon's counties (around 18%, according to the 2020 census). Also, like many rural Oregon counties, it also has a high percentage of Latino residents, with another 20% of the counties residents reporting Latino ancestry.