Why does the corps of discovery matter in the pages of history?

It doesn't matter. The Spanish pursued them 4 times because the Spanish had claim on the land. They eventually left their claim when the US signed the Treaty of Guadalupe Hidalgo, if it really was signed with full effect.

the right answer is the third one: turnpikes went short distances to connect markets. turnpikes, also known as toll roads, were very important for trade and transportation (of people, goods and products) in the 19th century, coinciding with the expansion towards the west. they contributed significantly to the economic development of the united states.