William Morris Davis (February 12, 1850 - February 5, 1934) was an American geographer, geologist and meteorologist, often called the "father of American geography".
He was born into a Quaker family in Philadelphia, Pennsylvania, son of Edward M. Davis and Maria Mott Davis (a daughter of the women's advocate Lucretia Mott). He graduated from Harvard University in 1869 and received a Master of Engineering in the following year. He then worked in Córdoba, Argentina for three years, then after working as an assistant to Nathaniel Shaler, he became an instructor in geology at Harvard, in 1879. (Davis never completed his PhD.) He married Ellen B. Warner of Springfield, Massachusetts in the same year.
His most influential scientific contribution was the cycle of erosion, first defined around 1884, which was a model of how rivers create landforms. Though the cycle is considered overly simplistic today, it was a crucial early contribution to geomorphology.
He was a founder of the Association of American Geographers in 1904, and heavily involved with the National Geographic Society in its early years, writing a number of articles for the magazine.
Davis retired from Harvard in 1911.
Later, after Ellen died, Davis married Mary M. Wyman of Cambridge, Massachusetts (1914), and she having died also, Lucy L. Tennant of Milton, Massachusetts (1928), who survived him.