Manifest destiny did not die when Americans successfully lay claim to the West Coast. The newly won territory was the source of heated argument in the 1850s and a major reason for the War Between the States. Once the Union was patched back together, Americans were mostly content with settling the land already under the United States flag. But as the decades passed and America grew strong with industrial might, the desire to spread the eagle's wings over additional territory came back into vogue. Between 1890 and the start of World War I, the United States earned a seat at the table of imperial powers.

By the time the United States got serious about looking beyond its own borders to conquer new lands, much of the world had already been claimed. Only a few distant territories in Africa and Asia and remote islands in the Pacific remained free from imperial grasp. Hawaii was one such plum. Led by a hereditary monarch, the inhabitants of the kingdom prevailed as an independent state. American expansionists looked with greed on the strategically located islands and waited patiently to plan their move.

There was more than one way to acquire more land. If the globe had already been claimed by imperial powers, the United States could always seize lands held by others. Americans were feeling proud of their growing industrial and military prowess. The long-dormant Monroe Doctrine could finally be enforced. Good sense suggested that when treading on the toes of empires, America should start small. In 1898, Spain was weak and Americans knew it. Soon the opportunity to strike arose.

The United States was simply unprepared for war. What Americans had in enthusiastic spirit, they lacked in military strength. The navy, although improved, was simply a shadow of what it would become by World War I. The United States Army was understaffed, underequipped, and undertrained. The most recent action seen by the army was fighting the Native Americans on the frontier. Cuba required summer uniforms; the US troops arrived with heavy woolen coats and pants. The food budget paid for substandard provisions for the soldiers. What made these daunting problems more managable was one simple reality. Spain was even less ready for war than the United States.

For many years, the Monroe Doctrine was practically a dead letter. The bold proclamation of 1823 that declared the Western Hemisphere forever free from European expansion bemused the imperial powers who knew the United States was simply too weak to enforce its claim. By 1900, the situation had changed. A bold, expanding America was spreading its wings, daring the old world order to challenge its newfound might. When Theodore Roosevelt became President, he decided to reassert Monroe's old declaration.

The United States could not ignore the largest continent on earth forever. Since Commodore Matthew Perry "opened" Japan in 1854, trade with Asia was a reality, earning millions for American merchants and manufacturers. Slowly but surely the United States acquired holdings in the region, making the ties even stronger. Already Alaska, Hawaii, and American Samoa flew the American flag. The Spanish-American War brought Guam and the Philippines as well. These territories needed supply routes and defense, so ports of trade and naval bases became crucial.

A canal was inevitable. A trip by boat from New York to San Francisco forced a luckless crew to sail around the tip of South America — a journey amounting to some 12,000 miles. The new empire might require a fast move from the Atlantic to the Pacific by a naval squadron. Teddy Roosevelt decided that the time for action was at hand. The canal would be his legacy, and he would stop at nothing to get it.

Isolation was a long American tradition. Since the days of George Washington, Americans struggled to remain protected by the mighty oceans on its border. When European conflicts erupted, as they frequently did, many in the United States claimed exceptionalism. America was different. Why get involved in Europe's self-destruction? When the Archduke of Austria-Hungary was killed in cold blood, igniting the most destructive war in human history, the initial reaction in the United States was the expected will for neutrality. As a nation of immigrants, The United States would have difficulty picking a side. Despite the obvious ties to Britain based on history and language, there were many United States citizens who claimed Germany and Austria-Hungary as their parent lands. Support of either the Allies or the Central Powers might prove divisive.

With American trade becoming more and more lopsided toward the Allied cause, many feared that it was only a matter of time before the United States would be at war. The issue that propelled most American fencesitters to side with the British was German submarine warfare.

When Congress declared war in April 1917, the army had enough bullets for only two days of fighting. The army was small in numbers at only 200,000 soldiers. Two-fifths of these men were members of the National Guard, which had only recently been federalized. The type of warfare currently plaguing Europe was unlike any the world had ever seen.

The First World War was a total war. In previous wars, the civilian population tried to steer clear of the war effort. Surely expectations were placed on civilians for food and clothing, and of course, since the 19th century, troops were conscripted from the general population. But modern communication and warfare required an all-out effort from the entire population. New weapons technology required excess fuel and industrial capacity. The economic costs of 20th century warfare dwarfed earlier wars, therefore extensive revenue raising was essential. Without the support of the whole population, failure was certain. Governments used every new communications technology imaginable to spread pro-war propaganda. American efforts geared to winning World War I amounted to nothing less than a national machine.

As the war drew to a close, Woodrow Wilson set forth his plan for a "just peace." Wilson believed that fundamental flaws in international relations created an unhealthy climate that led inexorably to the World War. His Fourteen Points outlined his vision for a safer world. Wilson called for an end to secret diplomacy, a reduction of armaments, and freedom of the seas. He claimed that reductions to trade barriers, fair adjustment of colonies, and respect for national self-determination would reduce economic and nationalist sentiments that lead to war.

The 1920s saw the culmination of fifty years of rapid American industrialization. New products seemed to burst from American production lines with the potential of revolutionizing American life. Other products that had previously been toys for the rich were now available to a majority of Americans. The standard of living increased as the economy grew stronger and stronger. The results were spectacular. The America of 1929 was vastly different from the America of 1919.

Although the technology for the automobile existed in the 19th century, it took Henry Ford to make the useful gadget accessible to the American public. Ford used the idea of the assembly line for automobile manufacturing. He paid his workers an unprecedented $5 a day when most laborers were bringing home two, hoping that it would increase their productivity. Furthermore, they might use their higher earnings to purchase a new car.

Saloons were closed, bottles were smashed, and kegs were split wide open. When the states ratified the Eighteenth Amendment in 1919, the manufacture, sale, and transportation of alcoholic beverages was outlawed. Protestant ministers and progressive politicians rejoiced and proclaimed a holier and safer America. It was predicted that worker productivity would increase, families would grow closer, and urban slums would disappear. Yet for all its promise, prohibition was repealed fourteen years later, after being deemed a dismal failure.

In the 19th century, the American world consisted of children and adults. Most Americans tried their best to allow their children to enjoy their youth while they were slowly prepared for the trials and tribulations of adulthood. Although child labor practices still existed, more and more states were passing restrictions against such exploitation. The average number of years spent in school for young Americans was also on the rise. Parents were waiting longer to goad their youngsters into marriage rather than pairing them off at the tender age of sixteen or seventeen. In short, it soon became apparent that a new stage of life — the teenage phase — was becoming a reality in America. American adolescents were displaying traits unknown among children and adults. Although the word teenager did not come into use until decades later, the teenage mindset dawned in the 1920s.

The battle for suffrage was finally over. After a 72-year struggle, women had won the precious right to vote. The generations of suffragists that had fought for so long proudly entered the political world. Carrie Chapman Catt carried the struggle into voting awareness with the founding of the League of Women Voters. Alice Paul vowed to fight until an Equal Rights Amendment was added to the Constitution. Margaret Sanger declared that female independence could be accomplished only with proper birth control methods. To their dismay, the daughters of this generation seemed uninterested in these grand causes. As the 1920s roared along, many young women of the age wanted to have fun.

It was time for a cultural celebration. African Americans had endured centuries of slavery and the struggle for abolition. The end of bondage had not brought the promised land many had envisioned. Instead, white supremacy was quickly, legally, and violently restored to the New South, where ninety percent of African Americans lived. Starting in about 1890, African Americans migrated to the North in great numbers. This Great Migration eventually relocated hundreds of thousands of African Americans from the rural South to the urban North. Many discovered they had shared common experiences in their past histories and their uncertain present circumstances. Instead of wallowing in self-pity, the recently dispossessed ignited an explosion of cultural pride. Indeed, African American culture was reborn in the Harlem Renaissance.

The 1920s was a decade of increasing conveniences for the middle class. New products made household chores easier and led to more leisure time. Products previously too expensive became affordable. New forms of financing allowed every family to spend beyond their current means. Advertising capitalized on people's hopes and fears to sell more and more goods.

Commercial radio in America had humble beginnings. Frank Conrad, an engineer for Westinghouse, set up an amateur radio station above his garage in a Pittsburgh suburb. Since the wireless technology was developed by Guglielmo Marconi in the late 19th century, thousands of enthusiasts across the world experimented with the new toy. After World War I, Conrad began broadcasting a variety of programming from his "station." High school music groups performed, phonograph records were played, and news and baseball scores were reported. Conrad had dramatically improved the transmitter, and soon hundreds of people in the Pittsburgh area were sending requests for air time. The bosses of Westinghouse knew that Conrad was on to something and convinced him to make his hobby commercially profitable.