The following is taken from Craven's History of Horsham.
The earliest recorded post office in Horsham Township was at the Friends Meetinghouse, which was located on the Doylestown and Willow Grove Turnpike, now Route 611, near the intersection of Meetinghouse Road. This was established on July 6, 1810 and the Postmaster was Charles Palmer. The Post Office was discontinued in the later part of 1823. In 1826, a regular Post Office was established; the first Postmaster being Charles Jarrett.
Usually a store located near a major crossroads would serve as a post office. In 1860 a store on the east side of Route 611, near Norristown Road was also a post office known as Horshamville . 0. P. Smith of Horsham served as Postmaster at this location for 50 years.
In 1854 a Post Office was established at Prospectville on the eastside of Limekiln Pike at the junction of Horsham Road. Nathan B. Johnson was the Postmaster. From 1864 to 1867, Thomas Yerkes was Postmaster, and from 1867 until 1903, C.B. Reading was Postmaster and store keeper at this location. In 1967, the Prospectville Post Office was discontinued, and its jurisdiction given to the Post Office at Ambler, Pa.
The Davis Grove Store at the corner of Governor’s and Privet Roads was post office for the village of Davis Grove and the surrounding part of the township. When Route 611 was completed to County Line Road in 1839, the village of Davis Grove lost its prominence as a major crossroads, and the village of Hallowell, located on Route 611 gained in prestige. When Charles Carr opened a new store in Hallowell, the post office was moved from the Davis Grove store to the residence of a member of the Jarrett family in Davis Grove. It is unclear as to when the Davis Grove Post Office was discontinued; but it is noted on the map as late as 1877.
The Charles Carr Store was located on Route 611, near Maple Avenue. The Hallowell Post Office was in Shanken’s store (now Grandma's Grotto) until 1954. In 1958, the post office was absorbed by the Horsham Post Office, and the Hallowell postmark discontinued.