Elwood is a city in Doniphan County, Kansas, United States, located across the Missouri River from Saint Joseph. As of the 2010 census, the city population was 1,224. It is part of the St. Joseph, MO–KSMetropolitan Statistical Area. A trading post was established at Elwood in 1852. In 1856, the site was sold and the town was then laid out. The town was named for John B. Elwood, a pioneer settler. Elwood was incorporated as a city in 1860.The first post office in Elwood was established in June, 1857.