John Day is a city located approximately 2 miles north of Canyon City in Grant County, Oregon, United States, at the intersection of U.S. Routes 26 and 395. The city was named for the nearby John Day River, which, along with Dayville, had been named for a Virginia member of the 1811 Astor Expedition, John Day. The city was incorporated in 1901. As of the 2020 census, the city had a total population of 1,664, making it the largest city in the county.