How did roads contribute to the empires sucsess?

The Roman introduced the stone-paved roads. Their purpose was military. They made the movement of troops and the transport of supplies to soldiers at the front or in garrisons fastest and easier. Therefore, they were important for the defense of the empire. They also made communication and the transport of goods for trade quicker and easier.  The paved roads were only 20% of the 400,000 kilometers (250,000 miles) of roads in the Roman Empire. They were the backbone of the overland communication and trade of the empire. The success of the empire was not only a military one. It was also a commercial one. The empire formed a huge trading network where large quantities of goods were bought, sold and transported all around the empire, creating prosperity

Explanation:

i believe it was spain

the constitution gives congress the power to regulate commerce "among" the several states.