Patrick J. Kiger

The country, from its commerce to the environment to even its concept of time, was profoundly altered after the completion of the railroad's 1,776 miles of track.

Since 1938, the U.S. federal government has established that workers are entitled to a base hourly wage. Which workers receive that minimum—and how much—has remained a political issue.

The Silk Road was a vital trading route connecting East and West—but it also became a conduit for one of history's deadliest pandemics.

A series of events escalated tensions that culminated in America's war for independence.

The future president’s break would not only help save his life, but also lead to his earning a Silver Star.

Battles in Africa were waged between colonial powers, but most of those compelled to fight were conscripted Africans.

The Middle Ages have yielded a series of amazing archaeological discoveries, from medieval swords to buried castle remains to evidence of zombie fears.

The firefighter deaths on Sept. 11 amounted to more than a third of the approximately 1,000 emergency personnel at the scene.

Overspending, lower oil prices and political unrest all combined to trigger a decline for the once-prosperous nation.

From Gerald Ford's football days to Barack Obama's basketball game to George W. Bush's impressive marathon splits, many presidents have shown athletic prowess.

Even though a widely-accepted account says the outlaw was shot by Sheriff Pat Garrett in New Mexico, murky details have led to other theories.

Ineffective leadership and a weak infrastructure during the war led to the demise of the Romanov dynasty.

The collection of laws and regulations carved into stone thousands of years ago carries principles and ideas that are still applied today.

The ancient Babylonian king ruled with military and diplomatic finesse—and he also knew a thing or two about self-promotion.

Environmental factors helped agriculture, architecture and eventually a social order emerge for the first time in ancient Mesopotamia.

One settlement in modern-day Illinois hosted a population of around 20,000, while another featured multiple-story buildings.

While the future president saw plenty of action in the Solomon Islands, at one station Nixon found time to master poker—and rake in winnings.

The 1911 factory blaze shocked the nation and spurred new regulations to protect factory workers.

Cruel efforts under Stalin to impose collectivism and tamp down Ukrainian nationalism left an estimated 3.9 million dead.

The Founding Fathers only set an age minimum for U.S. presidents—not a maximum.

Between 1946 and 1958 the United States detonated 23 nuclear weapons on the tiny, remote ring of islands that make up Bikini Atoll.

In 1519, Ferdinand Magellan set off on an audacious journey around the globe. Find out what made the expedition so dangerous—and why its leader did not survive.

Edison's genius was improving on others' technologies and making them more practical for the general public.

From kayaks to contraceptives to pain relievers, Native Americans from a range of tribal nations developed key innovations long before Columbus reached the Americas.

Republican president William H. Taft successfully advocated for a permanent, national income tax.

The surprise Japanese assault inflicted heavy losses but failed to strike a decisive blow.

The Revolutionary War officer-turned traitor had a brilliant strategy—except that everything went wrong.

The Greek city-state imposed brutal training and contests that began at age 7.

Both sides had suffered too much to continue, but Germany would be left battered by harsh terms.

There’s evidence that British colonists in 18th-century America gave Native Americans smallpox-infected blankets at least once—but did it work?

The period between the late 1800s and the early 1900s saw a boom in innovations that would take the world by storm.

The 400-year rule of the Han Dynasty generated a slew of innovations in everything from agriculture to metallurgy to seismology.

After the Romans conquered ancient Celtic realms, pagan traditions were adopted into a holiday honoring Catholic saints.

Chariot racing in ancient Rome showcased local teams, speed, violence and star athletes.

Ancient Greek athletes competed in individual sports that placed physical prowess on display.

Dressing in green on St. Patrick's can trace its roots to leprechaun legends, as well as a sign of Irish defiance.

It took grassroots efforts to raise the funds and ultimately build the colossal monument in New York Harbor that has come to symbolize freedom around the world.

From nourishing agricultural soil to serving as a transportation route, the Nile was vital to ancient Egypt's civilization.

The Civil War was a conflict many years in the making.

From George Washington to Dwight D. Eisenhower to John F. Kennedy, military veterans have risen to the nation's highest office many times through history.

Most famous for their role in the Boston Tea Party, the Sons of Liberty used grassroots activism to push back against British rule.

The 47-page pamphlet took colonial America by storm in 1776 and made critical arguments for declaring independence from England.

Crispus Attucks, a multiracial man who had escaped slavery, is known as the first American colonist killed in the American Revolution.

Franklin’s 'Join or Die' cartoon was so effective it rallied the colonies and influenced politics throughout two wars.

The Ottoman Empire was once among the biggest military and economic powers in the world. So what happened?

As they traveled west from the drought-ravaged Midwest, American-born migrants were viewed as disease-ridden intruders who would sponge off the government.

The Sumerian people of Mesopotamia had a flair for innovation. Here's how they left their mark.

Ancient Egyptians left behind a trove of artifacts that shed light on daily life during the civilization's 3000-year existence.

The script found on the insides of ancient Egyptian temples, monuments and tombs represents a complex remnant of history.

As Americans dreamed of amassing fabulous fortunes, many became vulnerable to cons.

While the vice presidency may seem like a prime launching pad, only 15 U.S. VPs have advanced to the highest office.

While the Industrial Revolution generated new opportunities and economic growth, it also introduced pollution and acute hardships for workers.

After his first battle in North Africa exposed U.S. weaknesses, Eisenhower regrouped, hired General Patton and led major military victories.

Imperialism, nationalistic pride and mutual alliances all played a part in building tensions that would erupt into war.

These are the steps that brought the United States and Soviet Union to the brink of nuclear war in 1962.

Ronald Reagan may have spearheaded the build-up that led to the demise of the Soviet Union, but George H.W. Bush quietly saw it through.

A ravine in the Ukrainian capital Kyiv was the site of a major 'Holocaust by bullets' carried out by Nazi forces during World War II.

While the British were often better equipped and trained, these events proved critical in ultimately securing Americans' victory in the war.

As American industrialists and financiers accumulated incredible wealth during the Gilded Age, they strove to outdo one another with their lavish spending and possessions.

Some disarmed the German military, while others stripped the defeated nation of territory, population and economic resources, and forced it to admit responsibility for the war and agree to pay reparations.

A surplus of U.S. corn crops led to a boom in whiskey sales—and consumption—following the Revolutionary War.

These battles were among the most pivotal in America's bloodiest conflict.

The 13 British colonies eventually joined to form the United States—but as colonies, they were often more different than they were alike.

By 1929, a perfect storm of unlucky factors led to the start of the worst economic downturn in U.S. history.

Strikes have been a powerful, sometimes perilous tactic for workers as they've fought for better wages and working conditions.

Postal mail delivery became a vital communication line for the colonies—and then helped unite the newly independent United States.

Before the invasion, the Allied commander was at odds with air force officers and Churchill over a controversial plan.

Runners were more reliable than any other form of communication. But the role was among the war's most dangerous.

Eliza Hamilton poured her energy into founding a free school and an orphanage in New York to help children in need.

If you can't hide from the enemy, confuse them.

The carnage of the war was so extreme that historians have had difficulty agreeing on exactly how many people lost their lives.

St. Augustine, Florida was founded by Spanish explorers long before Jamestown and the Plymouth Colony.

From regular infections to excruciating back pain, JFK contended with a range of physical challenges before and during his time in the White House.

In 218 B.C., the great Carthaginian general led his forces on a bold journey across the Alps to attack Romans on their home turf.

Death tolls weren't as high as in other wars, but the losses were significant for the population of the 13 colonies.

The April 15, 2013 bombing inflicted horror on a beloved Boston tradition and led to one of the most intensive manhunts in history.