Sawara has been settled since prehistoric times, and has numerous remains of Jōmon periodshell middens and Kofun periodburial mounds. By the Nara period, it had developed as a port, and as a monzenmachi associated with Katori Shrine, and in the Heian period was a regional commerce center for numerous shōen in the area. During the Edo period, it was partly under the control of the Omigawa Domain, a feudal domain of the Tokugawa shogunate. Modern Sawara Town was created in 1889. Sawara-city established on March 15, 1951 through merger with neighboring town of Katori and the villages of Kasai and Higashi-Oto. It expanded further on February 11, 1955 through annexation of the neighboring villages of Mizuho, Shinshima, Tsunomiya and Okura.
In February 2006 (the last data available before its merger into Katori), the city had an estimated population of 47,244 and a population density of 394 persons per km². Its total area was 119.88 km².
