The lost colony of Roanoke is one of American history's greatest mysteries. No one knows exactly how an entire colony located on Roanoke Island off the coast of North Carolina vanished. After it was established in 1584, a member of the had returned to England in 1587 for supplies — when he came home in 1590, he could find virtually no trace of the colony's populace.

Located in the Caribbean, the U.S. Virgin Islands were once called the Danish West Indies. However, the islands were not a particularly profitable colony, and Denmark tried several times to sell them to other imperial powers. Eventually, they found a buyer: the United States. They were formally transferred from Denmark to the U.S. on March 31, 1917, in exchange for $25 million in gold coin.

When the United States declared victory over Spain in the Spanish-American War in 1898, Puerto Rico officially became a U.S. territory. To this day, Puerto Rico has not been incorporated as a state, but many Puerto Rican citizens and those in local government have been continually pushing for statehood.

After the Founding Fathers signed the Declaration of Independence in 1776, it took 100 years for the original union to add another 25 members. On August 1, 1876, Colorado became the 38th state under President Ulysses S. Grant. At the time, the new state had a large population of miners, hunting for their fortunes in gold, silver, and coal mines.

In 1867, the U.S. purchased the Alaska territory from Russia for $7.2 million in gold, or about two cents per acre. The 586,000-square-mile territory was double the size of Texas. The move was considered foolish at the time, given Alaska’s remoteness and sparse population, but the state eventually proved to be industrially strategic.

The name “Idaho” has been traced to a Philadelphia-born man named George Willing, who fraudulently won an election in the territory that later became Colorado. Although he never took office, his idea that the territory be named “Idaho” managed to reach the U.S. Senate in 1860. Although Colorado was chosen instead, “Idaho” stuck around in popular consciousness, and it became the name of the new territory that broke off from the Washington territory in 1863.

After President Abraham Lincoln was elected in 1860, the Southern states started to secede over the issue of slavery. South Carolina was the first state to do so in December 1860. Before Lincoln’s inauguration in March 1861, seven states had seceded — Alabama, Florida, Georgia, Louisiana, Mississippi, South Carolina, and Texas — and the Civil War began in April 1861.

Spanning some 2,000 miles from Independence, Missouri, to Oregon City, Oregon, the Oregon Trail fueled a vast westward migration in the mid-1800s. Hundreds of thousands of early pioneers made the difficult journey by wagon along the historic trail, which passed through six states — Missouri, Kansas, Nebraska, Wyoming, Idaho, and Oregon.

Before it was a state, Maine existed as a province of Massachusetts for 143 years. However, residents of the province continually brought the idea of statehood to a vote between 1792 and 1819, mostly due to frustrations with the way the Massachusetts government treated their province. Finally, in 1819, the push for statehood gained enough support, and Maine became the nation's 23rd state on March 15, 1820.

When Mexico won independence from Spain in 1821 and expanded the Texas territory, it brought in settlers from the United States to help develop the land. Eventually, those settlers fought for and won independence from Mexico in the Texas Revolution. They established a short-lived independent Texas Republic before the U.S. annexed Texas in 1845.

In 1803, the United States paid France $15 million (about $345 million today) to acquire 828,000 square miles of territory that stretched from the Mississippi River to the Rocky Mountains. The area made up all or part of 15 present-day states, nearly doubling the size of the country. President Thomas Jefferson and future President James Monroe were both instrumental in negotiating the deal with Napoleon.

Early colonial settlers began founding villages west of the Appalachians in what became the state of Kentucky around 1775. As Kentucky expanded, Virginia claimed the region as part of its territory, making Kentucky a county in 1776. After the American Revolution, residents of Kentucky petitioned for separation from Virginia, and in 1792, Kentucky became the 15th state to enter the Union and the first state west of the Appalachian Mountains.

The Declaration of Independence — signed on July 4, 1776 — officially began the rebellion of the British Crown’s colonies in America. But it was Rhode Island that led the way two months earlier, on May 4, by becoming the first colony to renounce loyalty to King George III.

One oft forgotten part of the nation’s early colonial history was the colony of New Sweden. Established in 1638, it was the only Swedish foothold in North America, as well as the continent's smallest and shortest-lived colony. Located along the Delaware River, the colony covered parts of Delaware, New Jersey, and Pennsylvania.

In the early 1600s, Dutch settlers laid claim to land at the tip of what is now Manhattan, and the surrounding area was eventually called New Netherland. Its capital city was New Amsterdam, until the Dutch ceded control to the British Navy in 1664. New Amsterdam’s name was changed to New York, in honor of the Duke of York’s part in the mission.

Washington, D.C. was established as the nation's capital in 1800, but before that eight different cities served as the capital for at least some period of time. Lancaster, Princeton, and New York City were on the list, but Dover was not.

Before Florida was annexed into the United States, it was colonized by the Spanish. Explorer Pedro Menéndez de Avilés established the first permanent European settlement in the U.S. at St. Augustine in 1565. Before that, it was the domain of Indigenous groups such as the Seminole peoples. Florida became the 27th state in 1845.

In 1607, 13 years before the Pilgrims even spotted Plymouth Rock, the first permanent British colony in what would become the United States was established at Jamestown in Virginia. The colonists, who were part of the Virginia Company of London, named the settlement after King James I. In 1624, Virginia became England’s first royal colony in the U.S.

The first settlers of Hawaii were the Polynesians, who arrived in the eighth century. In the 1800s, American traders and missionaries arrived on the islands, and the U.S. realized Hawaii’s strategic importance during the Spanish-American War. The islands became a U.S. territory in 1900, but it wasn’t until August 21, 1959, that Hawaii became the 50th state under President Dwight Eisenhower.

Delaware is nicknamed “the First State,” and for good reason: On December 7, 1787, Delaware became the first of the original 13 colonies to ratify the United States Constitution. Pennsylvania, New Jersey, Georgia, and Connecticut followed Delaware as the next states to ratify the Constitution. Delaware may be “the First State,” but it ranks 49th in land area — only Rhode Island is smaller.

Many of the key events leading up to the founding of the United States — including the signing of the Declaration of Independence — took place in Philadelphia, so it made sense that it was the first of nine cities to serve as the U.S. capital. The First Continental Congress took place in Philadelphia at Carpenter's Hall in 1774.