How many miles of paved roads are there in the U. S.? How would you attempt to find the answer?

(The solution number isn't exactly important here, more like the critical thinking of how you got that with the process)
ie. Factoring density, grouping of more dense states, less dense states, or the ratio between paved roads and people. Any ideas? Thanks!

sorry? idk what i'm supposed to exain and i might

the first phase of the government’s plan for settlement was building the transcontinental railroad. the railroad provided a way to bring settlers and manufactured goods west and ship their agricultural and mining produce east. the transcontinental railroad was an essential artery for rapid development of the frontier.

the second phase of the government’s plan was a liberal land distribution policy that made it possible for many people to homestead. with these two key elements—transportation and cheap land—the government rapidly achieved its goal of persuading people to move west, settle on farms, and push back the frontier.