Final answer:
The early twentieth century saw the number of paved roads increasing due to the popularity of automobiles, leading to the growth of suburbia and altering social and economic patterns.
Step-by-step explanation:
The increasing popularity of automobiles during the early twentieth century fundamentally transformed the United States by accelerating the development of infrastructure, particularly roads. The most accurate statement reflecting this change is that the number of roads that were paved increased. The onset of the automobile era sparked a surge in road construction to facilitate the new transportation needs of the American public. This, in turn, supported the proliferation of suburbia and changed the social and economic landscape, leading to suburban sprawl outside the congested city centers.
The advent of automobile culture rendered the previous reliance on streetcar and rail-based mass transit systems obsolete for many. People could now live farther away from their workplaces and the urban hubs, resulting in a demographic shift from densely populated city districts to more spread-out suburban communities. As roads stretched across the nation, supporting services such as motels and restaurants emerged to cater to the mobile population driving the new American economy.