Which legislation reflects federal efforts to regulate transportation?

The Interstate Commerce Act is a key piece of legislation that laid the groundwork for the federal regulation of transportation in the United States. Enacted in 1887, this act was primarily aimed at regulating the railroad industry, which was crucial for interstate commerce. It established the Interstate Commerce Commission (ICC), the first federal regulatory agency, which was responsible for overseeing railroads to ensure fair rates and to prevent discriminatory practices.

The significance of this act lies in its recognition that transportation is a matter of national concern, as it directly impacts economic activities that cross state lines. By regulating interstate railroads, the law sought to eliminate monopolistic practices and promote competition, which was essential for the burgeoning economy of the time.

Other options, while also significant in the landscape of transportation legislation, either focused on specific aspects of transportation or were enacted later. For instance, the Federal Aid Highway Act primarily provides funding for highway construction; the Transportation Equity Act addresses broader issues related to transportation funding and equity; and the Railroad Safety Improvement Act focuses specifically on safety measures in rail transport. However, the Interstate Commerce Act is the foundational legislation that specifically established federal authority over interstate transportation, making it the best answer to the question.