Question

review the details below.

• the transcontinental railroad allowed access to previously untapped natural resources from the west and midwest, leading to a boom in u.s. manufacturing.
• freight and passengers crossed from the east to the west more quickly and cheaply than ever before once the transcontinental railroad was completed in 1869.
• smaller railroads connected to the transcontinental opened new lands to settlement and allowed thousands of new towns to be built.

choose the best topic sentence to introduce a paragraph containing these details.
americans traveled to thousands of new places in the west as a result of the transcontinental railroad.
industries on the east coast produced more goods once the transcontinental railroad was finished.
the transcontinental railroad benefitted the american economy by opening up the midwest and west coast to the rest of the u.s.

Explanation:

The details discuss how the transcontinental railroad boosted manufacturing (economic impact), improved transportation, and enabled settlement/development. The third option ("The transcontinental railroad benefitted the American economy by opening up the Midwest and West Coast to the rest of the U.S.") encompasses all these benefits (economic, transportation, territorial development) related to connecting the Midwest/West to the rest of the US. The first option focuses only on travel/settlement, and the second only on East Coast industries, while the third is broader and matches the overall theme of the details.

Answer:

The transcontinental railroad benefitted the American economy by opening up the Midwest and West Coast to the rest of the U.S.