Which of the following was NOT a direct consequence of the building of railroads in the United States?

The establishment of a series of national parks was not a direct consequence of the building of railroads in the United States. While the expansion of railroads did contribute to greater access to natural landscapes and increased tourism, the formal creation of national parks was driven by other factors, such as the growing conservation movement and the efforts of individuals like John Muir and Theodore Roosevelt. The movement to preserve these areas emerged as people recognized the need to protect natural resources and the beauty of the American wilderness, rather than being a direct result of railroad construction.

In contrast, the expansion of the steel industry, the adoption of standardized time zones, and the growth of the American engineering profession are direct results of railroad development. Railroads required vast quantities of steel for tracks and infrastructure, leading to the steel industry's expansion. The need for consistent scheduling and coordination of train travel prompted the establishment of standardized time zones in 1883. Additionally, the complexity of railroad construction and operations spurred advances in engineering and the growth of the profession, necessitating skilled engineers to design and manage these vast systems.