It promoted the (relatively) rapid diffusion of immigrants, language, and domesticated crops and animals. Those factors are examined in excellent detail in Jared Diamond's book, "Germ, Guns and Steel" which I highly recommend for anyone studying the development of world cultures. It's a long read, but well worth it.
Nationalism-the loyalty and devotion to one's nation.
For one, people in America were like "lets go to war with Britain" which spurred the War of 1812. So if that's any correlation to how it affected foreign affairs, there ya go.
Our foreign affairs were affected because we were proud to be Americans. We got more active in conflicts and defended our country and its people mainly due to agrarianism (You'll probably learn about that in US History in HS), which was the belief Thomas Jefferson had that if people owned land, they would fight for this country.
To really answer your question, we were on and off friends with our foreign comrades. We went to war as a result, and established our power in the world.
<span>People saw the grim effects of war for the first time in his graphic photos</span>
The steam locomotive allowed for the transportation of goods at a much more rapid rate than by horse. The railroad let people know exactly where and when goods would arrive. The trains also gave the cargo a safer ride as it was much more difficult to rob a train than a horse drawn transport. As more railroads were built, products could travel farther than ever before in a timely manner. This brought down the cost of freight transport and increased profits for many businesses.