As America pushed westward, old divisions over slavery deepened — setting the stage for Civil War.

America was halfway through its first full century as a free nation in 1850. Its population numbered more than 23 million people, not including slaves, who wouldn’t be counted until the 1860 U.S. Census.

At the start of the decade, Americans lived in 30 states. By year’s end California would join the Union as the 31st state. The U.S. also governed four organized territories.

Most Americans still lived in rural communities and farmed for a living. The young nation’s largest city, New York, had more than 500,000 residents.

The population continued to grow as thousands of Irish immigrants fleeing the Great Famine of the 1840s took their chances at a better life in America.

Meanwhile, the country was expanding westward. “Forty-Niners” with gold fever rushed to California in search of fortune, and settlers driven by the belief in “Manifest Destiny” pushed into the Oregon Territory and vast new lands ceded by Mexico after the Mexican-American War.

But expansion brought new tensions and deepened the national divide over slavery — a crisis only temporarily eased by the Compromise of 1850.

Here are some of the events, people and milestones that made headlines in the 1850s.

Many modern Americans may not realize how close the nation came to Civil War in 1850. That June, delegates from nine Southern states met in Nashville to discuss secession.

The debate centered on whether new territories carved from the West would allow slavery. When California applied for statehood as a free state in 1849, it threatened to upset the fragile balance between free and slave states established by the Missouri Compromise of 1820. That agreement had admitted Missouri as a slave state, Maine as a free state, and banned slavery north of latitude 36°30′ north in the Louisiana Territory.

Led by Sen. Henry Clay of Kentucky, Congress debated for months before adopting a package of five bills that became known as the Compromise of 1850 — including several compromise bills proposed by Sen. Stephen Douglas of Illinois.

Enacted in September, the compromise admitted California as a free state, organized Utah and New Mexico as new territories, settled the disputed boundary of Texas, abolished the slave trade in Washington, D.C., and strengthened the Fugitive Slave Act. The new law required federal and local authorities in all states to capture and return suspected fugitive slaves.

The compromise diffused tensions that led the nine Southern states to discuss succession from the Union. In November 1850 they reconvened and concluded that the congressional compromise was satisfactory.

The westward migration of restless Americans in search of opportunities was in full swing by the 1850s. Many Americans embraced “Manifest Destiny,” the belief that expansion from coast to coast was inevitable and divinely ordained.

Fueled by the 1848 discovery of gold in California Territory, Americans by the thousands headed west overland or by ship around South America. Some sailed to Panama, trekked to the Pacific Ocean and boarded another ship for San Francisco. California’s non-native population exploded from about 800 in 1848 to more than 100,000 by 1850. The Compromise of 1850 granted California statehood that September.

Lured by cheap land, Americans also migrated to Oregon Territory. Others migrated to territories gained from Mexico, adding more than 525,000 square miles to the United States.

Immigration from overseas also continued. The Great Famine in Ireland ended around 1850, but immigration continued well into the decade. Many Germans and Scandinavians arrived as well. On the West Coast, Chinese laborers came to work in the gold fields, farms and factories. They would later be instrumental in building the transcontinental railroad.

The Compromise of 1850 only delayed the inevitable clash over slavery fueled by expansion.

In 1854, Congress passed the Kansas-Nebraska Act, which divided the land immediately west of Missouri into two new territories. The bill allowed residents of the territories to decide whether or not to permit slavery.

The result was chaos and bloodshed. Proslavery and antislavery settlers flooded into Kansas, and violence soon followed.

One of the most infamous characters to emerge was John Brown, who joined five of his sons in Kansas Territory in 1855. He became an antislavery guerrilla leader, fought off an attack on the antislavery town of Lawrence and retaliated by murdering five unarmed men and boys at the proslavery settlement of Pottawatomie Creek.

Brown’s violent crusade continued until 1859, when he led a raid on the federal arsenal at Harpers Ferry, Va., hoping to spark a slave revolt. Local militia and U.S. Marines led by Robert E. Lee quashed the raid. The wounded Brown was captured and hanged, along with six of his men.

The Kansas-Nebraska Act also led to the 1854 founding of the Republican Party in Pittsburgh, uniting anti-slavery leaders from several political parties under a new banner to oppose the extension of slavery.

Most Americans in the 1850s still lived simply in rural communities, building their own homes, growing their own food, and making their own clothing. They got their news from newspapers, magazines, books and word-of-mouth.

In 1852, readers in the North were captivated by Harriet Beecher Stowe’s “Uncle Tom’s Cabin,” first serialized over 40 weeks in the abolitionist newspaper The National Era. The novel humanized enslaved people and exposed the cruelty of slavery, selling 300,000 copies in its first year in the U.S. and England. The novel was adapted for the stage, as theater melodramas were popular entertainment at the time. The book was widely denounced in the South.

Other landmark works included Nathaniel Hawthorne’s “The Scarlet Letter,” published in 1850; Herman Melville’s “Moby Dick” in 1851; and Henry David Thoreau’s “Walden” in 1854.

Journalist Henry J. Raymond published the first issue of The New York Times in 1851, and Harper’s Weekly began publishing in 1857.

Popular Swedish opera singer Jenny Lind, promoted by showman P.T. Barnum, toured the U.S. in 1850 and 1851 to frenzied acclaim dubbed “Lind mania” by the press.

On Feb. 1, Edward “Eddie” Lincoln died in Springfield, Ill., from consumption. Just 4 years old at the time, Eddie was the son of Abraham and Mary Todd Lincoln.

Feminist, author and literary critic Margaret Fuller, famous for her 1845 book “Woman in the Nineteenth Century,” died tragically with her family in a shipwreck off Fire Island, N.Y., in July 1850. She was 40 years old.

Also in July, President Zachary Taylor — a hero of the Mexican-American War — died from an illness in the White House. Vice President Millard Fillmore took over as 13th president.

The 1850s brought a surge of inventions that made everyday life easier and paved the way for modern industry.

In 1850, inventor Joel Houghton patented the first dishwasher — a crude wooden machine that splashed water on dishes when a wheel was cranked. Though ineffective, it inspired later innovations that led to the modern dishwasher in 1889. It used pressurized water to clean dishes.

That same year, Isaac Singer redesigned an early sewing machine by adding a foot pedal, enabling 900 stitches per minute compared with 40 by an accomplished seamstress. Singer marketed the machines to housewives for $10 each.

In 1851, Elias Howe, who had patented an early sewing machine in 1846, patented an “automatic, continuous clothing closure.” The garment fastener was the grandfather of the zipper.

James King patented the first hand-powered drum-style washing machine in 1851, while Matthew Brady earned medals for his portrait daguerreotypes at London’s Great Exhibition that same year. Cyrus H. McCormick also won accolades there for his mechanical reaper, invented in 1831.

In 1853, Elisha P. Otis demonstrated a safety brake for elevators in New York City, a breakthrough that allowed passenger elevators to, well, take off.

And on Aug. 27, 1859, former train conductor Edwin Drake drilled the first successful oil well along the banks of Oil Creek near Titusville, Pa. Drake pioneered several new drilling techniques that helped launch the modern petroleum industry.

Political violence is not a modern phenomenon in America.

On May 22, 1856, Congressman Preston Brooks of South Carolina entered the Senate chamber and viciously beat Sen. Charles Sumner with a cane. Brooks was responding to a speech the anti-slavery senator from Massachusetts had delivered days earlier mocking Brooks’ relative, Sen. Andrew Butler, who had co-authored the Kansas-Nebraska Act.

Sumner suffered severe injuries but eventually returned to the Senate. Brooks was arrested and fined $300. He resigned from Congress and later died in 1857 of an infection at the age of 37.

The incident foreshadowed the violence that would erupt over the issue of slavery five years later and political violence still occurring today in America.

In 1858, Republican Abraham Lincoln was running for a Senate seat representing Illinois. He challenged incumbent Democratic Sen. Stephen Douglas — co-author of the Kansas-Nebraska Act — to a series of debates.

During the seven debates, Lincoln and Douglas argued the issue of extending slavery into Western territories. Though Lincoln lost the election, the debates established him as an eloquent speaker on the issue of slavery and set the stage for his 1860 presidential campaign.

In March 1857, the U.S. Supreme Court issued its infamous Dred Scott v. Sandford decision, ruling that all people of African ancestry — whether enslaved or not — were not U.S. citizens and had no legal rights or protection.

The case began in 1846 when Dred Scott and his wife, Harriet, sued for their freedom in St. Louis, arguing that because they had once lived in a free territory they were entitled to emancipation.

The Court not only rejected their claim but also declared that Congress lacked the authority to prohibit slavery in the territories — a decision that inflamed sectional tensions and led the nation closer to Civil War.

The Dred Scott ruling was effectively overturned after the Civil War by the 13th Amendment to the Constitution, which abolished slavery, and the 14th Amendment, granting citizenship to anyone born in the United States.

Fueled by westward expansion, gold discoveries and the Industrial Revolution, the U.S. economy boomed through most of the 1850s. The nation added 20,000 miles of railroad track, factories expanded and the number of banks nearly doubled between 1850 and 1857.

It all came crashing down in 1857.

The panic began when the Ohio Life Insurance and Trust Company collapsed in late August, triggering a wave of bank failures. As confidence evaporated, depositors withdrew gold, stock prices plummeted and businesses folded. Construction on buildings and the railroads halted, crop prices fell and unemployment soared — especially in the Northeast and Midwest.

Some savvy investors, like Cornelius Vanderbilt, seized the opportunity to buy up cheap stocks and failed businesses. In St. Louis, a farmer and former soldier named Ulysses S. Grant, hurt by low crop prices, pawned a gold watch two days before Christmas.

The panic subsided by spring 1858, but recovery took two full years.

The 1850s were a pivotal decade of explosive growth, restless migration, bold innovation and rising tensions over the issue of slavery that propelled the nation inexorably toward Civil War.

As the decade closed, the election of Abraham Lincoln in 1860 became the spark that ignited the proverbial powder keg — plunging America into the bloodiest conflict in its history.