Road transport (British English) or road transportation (American English) is the transport of passengers or goods on roads. This transport method can be via bike or automobiles or by animal such as horse or oxen. Standard networks of roads were adopted by Romans, Persians, Aztec, and other early societies. Modern roads came into adoption during the late 1700's with civil engineering.
Cargo may be transported by trucking companies, while passengers may be transported via mass transit. Commonly defined features of modern roads include defined lanes and signage. Within the United States, roads between regions are connected via the Interstate Highway System.
The first methods of road transport were horses, oxen or even humans carrying goods over dirt tracks that often followed game trail. The Persians later built a network of Royal Roads across their empire.
With the advent of the Roman Empire, there was a need for armies to be able to travel quickly from one area to another, and the roads that existed were often muddy, which greatly delayed the movement of large masses of troops. To resolve this issue, the Romans built great roads. The Roman roads used deep roadbeds of crushed stone as an underlying layer to ensure that they kept dry, as the water would flow out from the crushed stone, instead of becoming mud in clay soils. The Islamic Caliphate later built tar-paved roads in Baghdad.