Why did railroad construction expand so rapidly after the civil war

Which term best describes the progressive era

What was the most important consequence of the large-scale ecological changes in africa two hundred thousand years ago?

What is the significance of the battle of saratoga? a. the defeat at saratoga allowed the british to invade new england by land. b. after the defeat at saratoga france refuse to sign a treaty with the united states. c. the british won a decisive victory at saratoga. d. after the victory at saratoga france gave open support to the united states including arms money and ships.