Two dominant individuals made the early settlement of Zillah possible. Thomas F. Oakes, president of the Northern Pacific Railroad, entrusted a man named Walter N. Granger to fulfill his vision for him of transforming the arid, desert land of the lower valley into a lush green valley of agricultural productivity by means of irrigation from the nearby Yakima River. After studying the matter for a few days Granger decided to assume the challenge before him. During the 1890’s, the Sunnyside canal project was begun. With construction out of the way, the promoter and sole superintendent of the canal, Granger selected a town site in 1892. The question of name the town arose from the site itself. During the visit, the decision was made to name the town Zillah, in honor of Miss Zillah Oakes, daughter of the railroad company president.
Development of the town site occurred quickly. Shortly after, a hotel was built. Soon a general store, drug store and a blacksmith shop were added. During 1894, School District #32 was organized and a schoolhouse was built. By the time the branch rail line came through Zillah, the area had two stage lines and two telephone lines. The growing settlement was incorporated in 1911, and by 1920 had a population of 647. The economic growth of Zillah settlement was made possible through the delivery of irrigation water to its arid desert land. Since 1970, Zillah has been growing at the fastest rate in history. Today it continues to grow but those who live here continue to enjoy the small town life.