The Bulldozer

Credited to Kansas farmers James Cummings and draftsman J. Earl McLeod. The Bulldozer as we know today is a quintessentially American device emerging in the 1920s as a mechanized version of a formerly human or animal powered agricultural implement which used a vertical wooden blade to smooth rough ground for farmers. Bulldozers back then weren’t originally built as bulldozers; they were simple track-laying traction engines with the scraper blade at the front of the machine being the bulldozer and the machine was referred to as a crawl tractor (they were basically a tractor with a blade attached at the front). Though the original bulldozers were meant for agricultural purposes, they were quickly used for construction and even World War 2 as bulldozers would be used to clear obstacles, roads as well as bomb filled crates and remove disabled aircraft. They would also be used to construct highways and fortifications during the war and eventually for modern day construction as well.

Here's an example of an early bulldozer.