The change in currency to paper money
An economic panic that started in 1873 introduced an issue that would continue for the rest of the 1800s. During the Civil War, the Union had issued millions of dollars in paper money. People who owed loans wanted more paper money, because that would increase inflation. Inflated cheap money would make the debt they owed easier to repay. The cheap-money people also supported the coinage of silver to bring about more inflation. Businessmen who loaned money wanted all paper money paid off in gold, so that the money they loaned would be worth more when it was paid back. The U.S. Treasury, backed by businessmen, redeemed paper money for gold so regularly that, after a while, people got tired of carrying jangling coins and just used paper money instead.
When a country loses 600,000 men in a war, you'd expect the population to go down for a while. The South lost 1 out of 10 adult males, the North 1 out of 30; the equivalent loss in today's U.S. population would be 6 million people. But the United States was the most popular immigration destination in the world. The population of the country actually went up by more than 25 percent during the Civil War decade; by 1870, the United States had almost 40 million citizens. Lots of these people were moving to Eastern cities or opened Western land. With no real danger of foreign attacks or internal dissolution, the United States turned to wrangling about money and voting rights.
The history of the post-Civil War United States centered on moves to the cities and to the West. The Civil War was a fight among farm boys; 80 percent of Americans at that time lived in the country. But by 1900, the United States was only 60 percent rural and boasted several cities over 1 million in population. New York had become the second-largest city in the world.
Europe was growing too. Thanks in part to food imported directly from America and to European cultivation of that New World wonder food, the potato, the population of Europe doubled in the 1800s.
Many Europeans were moving around that continent, looking for new opportunities. For some people — like the Irish living in famine — the choice was immigrate or die. Aided by the ease and cheapness of steamship travel, 20 million Europeans made the jump across the Atlantic to the United States between 1820 and 1900.
As in the Know-Nothing days before the Civil War, the increase in immigrants and the growth of cities worried some traditionalists. As the 1870s drew to a close, calls to restrict immigration grew louder.