Deerfield Township, one of eleven townships of Warren County, Ohio, USA, is located in the southwest corner of the county. The most urbanized of the eleven, it had 25,515 people in the 2000 census and 26,359 in 1990. (The drop is because the city of Mason, which was included in the 1990 figures, withdrew from the township in February 1997.) Until 1997, Kings Island amusement park was in the township.


The county is bounded on the west by the Butler County townships of West Chester and Liberty; on the north by Turtlecreek and Union Township; on the east by the Little Miami River (and across the river by Hamilton Township; and on the south by the Hamilton County townships of Symmes and Sycamore.

One of the original four townships of Warren County, it was created on May 10, 1803, when the county was just nine days old. As originally created, it included all of what is now Union, the southern part of Turtlecreek Township, and Salem north of the Little Miami River.

The township is governed by a three-member board of trustees, who are elected in November of odd-numbered years to a four-year term beginning on the following January 1. Two are elected in the year after the presidential election and one is elected in the year before it. There is also an elected township clerk, who serves a four-year term beginning on April 1 of the year after the election, which is held in November of the year before the presidential election. Vacancies in the clerkship or on the board of trustees are filled by the remaining trustees. Voters in 2002 rejected a proposal to expand the board of trustees to five members.

Communities within the township include Kings Mills, Snidercrest, Fosters, Socialville, Twenty Mile Stand, Loveland Park, Landen, and Loveland.

Most of the township is in the Mason City and Kings Local School Districts, but the extreme southwest corner of the township is in the Princeton City School District. Telephone service is provided through the Mason exchange through most of the township, but the southeastern part is in the Little Miami exchange. Mail is provided through the Mason, Lebanon, Kings Mills, Maineville, and Loveland post offices and the Sharonville and Sycamore branches of the Cincinnati post office.