Final answer:
Slow transportation and high costs; railways
The downside of overland transportation was slow speed and high costs, and the most efficient way to move goods from the interior to the east coast during the early 1800s in the United States was via railways.
Step-by-step explanation:
The downside of transporting goods overland in the United States during the early to mid-1800s was primarily slow transportation and high costs.
Though there were various methods for moving goods, the question seeks to identify the most efficient mode of transportation from the interior to the east coast.
The correct choice is A: Slow transportation and high costs; railways. As the country industrialized, and with the advent of the transportation revolution, railroads became an essential infrastructure for moving goods.
In comparison to canals and roads, railways provided a faster and more reliable method for transporting goods, despite the fact that initially canal transport was cheaper.
According to historical context, it was very costly to ship materials overland. Before the widespread use of railroads and canals, it could cost as much to send a ton of material thirty miles overland as it did to send that same material across the Atlantic to Europe.
With the construction and expansion of railroads in the 1830s, the United States saw the establishment of an extensive and dominant transportation network by the 1850s, linking the interior with port cities and supporting the development of a national market system.