This township was formed in 1836, by the division of Deer. Its area had previously been considerably curtailed by the formation of Indiana in 1805. As thus reduced, Deer was a narrow, rectangular township extending about sixteen miles along the Butler county line, and about six miles wide. West Deer received the larger part of this territory, and its limits included portions of Hampton and Richland in addition to its present area. Within the territory now comprised in its limits, the first settler was Benjamin Paul, a "squatter," who made a clearing, built a cabin and planted an orchard prior to 1800, on land subsequently owned by the Hazletts, who came before 1800. There were two brothers, James and William Hazlett, from Ireland, as were many of the settlers in this region. The sons of James were William, George, James, John and Alexander; of William, James, John and William. Their descendants are still on the ancestral estates.

Jeremiah Smith was the original owner of some of the land purchased by the Hazletts. He removed to Butler county. John Carnahan came prior to 1800, and settled in the northeast part of the township, about a mile from the line of Butler county. He remained here till his death, in 1830. His sons were George, Samuel and John, the last still living on the old place. George was a soldier under Gen. Harrison in the war of 1812. David Ferguson came at about the same time, and settled near Mr. Carnahan, where he also remained till his death. His sons were Samuel and William, both dead. Thomas Stewart was also a settler prior to the commencement of the present century, and passed his life here. His son William removed to the west, where he died. James Jack and his brother Andrew were also original settlers. The sons of Andrew were James, John, Leslie and Samuel. Robert Glasgow, the first blacksmith in the township, was an early settler. The property which he owned is still in possession of his descendants. Thomas McConnell, the first tavern-keeper, was here early, and had his hostelry on the Harmarville road. His sons were Hugh, George, John, Thomas and James. Nehemiah Bell was an early settler. His son Samuel is still on the place which he settled. William Leslie was an original settler. He had several sons, and his grandson James resides on the old homestead. Henry Kissick had sons James, Joseph, Samuel, Moses and Clark. His descendants are on the old place.

In addition to these the following were early residents: William McClelland, Elias Thomas, Robert Porter, Robert Norris, John McCool, Robert Hemphill, Thomas Love,
Alexander Black, Robert Caldwell, Henry Hultz, Robert and Hugh Cunningham. Michael Carlisle, John Donaldson, John McGowan, Robert Hague, James Fleming, James Boyd,
Robert Thompson, John Thompson, James and Thomas Hamilton, William McAllister.

Robert Thompson was an early owner, and probably the builder, of a gristmill on Deer creek, in the southwest part of the township. It long since went to decay. There were in the township several small mills, driven by horsepower.

Deer creek, Little Deer creek. Bull creek and the Connoquenessing have their sources in this township, which is the largest in the northern part of the county, being about five miles square; and it is also one of the most fertile and wealthy. The population in 1860 was 1,865; in 1870, 1,299; in 1880, 1,438. Oil and gas have recently been discovered in West Deer, and prospecting is in active progress. Visions of great wealth in the near future arise in the imaginations of many, and the price of real estate is consequently enhanced. It is still too early for confident predictions.

Of the three postoffices, Rural Ridge was first established in 1853. Culmerville dates from January, 1854. Lewis was so named from Jane Lewis, who was appointed to the office in 1883. With the possible exception of Culmerville, there is no village in the township. A murder was once committed near this place, which was afterward popularly called "Brimstone Corners," a name which is not yet quite obsolete.

The first schoolhouse, on land of John Hazlett, was built prior to 1800. Six schools are now in operation.

Bull Creek Presbyterian Church was organized in 1796. Rev. William A. Boyd was pastor in 1802-33. Revs. Samuel Caldwell, J. Johnston and Thomas W. Kerr were also among the earlier pastors. East Union United Presbyterian Church was organized June 3, 1850. Pastors: J. Given, 1854-57; W. Weir, 1866-69; J. A. Brandon, 1871-76; J. M. Witherspoon, 1877-82; W. F. Miller, 1884-. Deer Creek United Presbyterian Church was organized in 1802. Pastors: J. McConnell, 1811-45; A. G. Shafer, 1847-68; S. M. Hood, 1870- There is also an old Covenanter church in the northeastern part of the township.