Horsham Township is named after the town of Horsham in Sussex in the South of England. Horsham is one of several townships in Montgomery County whose name and size were determined by master survey lines drawn by William Penn's engineers as they first plotted this part of the colony for sale and settlement. Parallel lines, projected at intervals of a mile and a half and extending in a northwesterly direction from settlements along the Delaware, served not only as base lines for measurement of individual land grants but also as courses for future highways. County Line Road, Horsham Road, and Welsh Road are examples of highways so laid out. The effect of these survey lines upon the development pattern of Eastern Montgomery County is very much in evidence today.