Period 4 (1800 – 1848) spans the election of Thomas Jefferson to the Treaty of Guadalupe Hidalgo – which ended the Mexican-American War. This time in America history can best be summarized by one word: expansion. The United States was marked by expansion in almost every area of life. Politically, the election of Jefferson ushered in a Jeffersonian belief encouraging participation in government by the educated “common man”; with a new attitude toward political equality, America witnessed a historical expansion as more men actively participated in politics.

Economically, the First Industrial Revolution unleashed new technologies and markets across America, leading to an expansion in the scope, size, and prosperity of the American economy. Socially, cities across the Northeast expanded dramatically as immigrants poured into America seeking economic opportunities. Additionally, the Treaty of Guadalupe Hidalgo expanded the United States from the Atlantic to the Pacific, allowing America to stretch continentally.

The election of Thomas Jefferson in 1800 signaled the decline of the Federalist party – a party typically characterized as “elite”- and cemented the Jeffersonian belief in the capability of the educated common man. Across the country, white men began to see themselves as equals across socioeconomic classes. This feeling of equality led to a surge in political participation nationwide. After America’s victory in the War of 1812, a sense of nationalism swept through the country and ushered in the short-lived “era of good feelings.” With the demise of the Federalist party, America experienced a sense of equality and unity. However, the “era of good feelings” was short-lived, as the booming economy exposed regional rifts which soon turned into regional chasms.

The First Industrial Revolution was characterized by a rise of industrialization and ease of transportation across the nation. Technological advances increased labor efficiency, while the steam engine and expanded canals made transporting goods faster and cheaper than ever before. Aiding America’s transformation into a powerful economy, Henry Clay proposed the “American System” to economically connect the regions and create a “national market economy.”

However, as manufacturing began to boom in the North, economic forces encouraged the South to focus on providing cotton. Eli Whitney’s cotton gin made widespread cotton production economically profitable, so long as labor was plentiful and cheap. As the South’s economy relied more heavily on cotton, the institution of slavery became more ubiquitous with the South. So, while the North embraced a manufacturing revolution in a diverse economy, the South solidified itself as a homogeneous economy increasingly reliant on slave labor. As the nation expanded, this economic, cultural, and social dichotomy would prove irreconcilable.

Not only was the young nation expanding socially, economically, and politically, it also expanded in sheer size. The idea of Manifest Destiny captured the imagination of America and gave the government license to pursue westward expansion at all costs. Jefferson began this expansion with the Louisiana Purchase – which doubled the land mass of America overnight. The Treaty of Guadalupe Hidalgo solidified America’s continental conquest by forcing Mexico to cede the lands of current-day Texas, Arizona, New Mexico, Nevada, Utah, and California.

For Northerners, the western frontier offered an escape from overpopulated cities and the chance to take ownership of one’s economic future. For Southerners, the western frontier represented additional, fertile farmland which could be used to increase economic clout in the world economy. As Americans poured over the Appalachian Mountains, this expansion was marked by conflict – both with Native Americans, and among Northerners and Southerners. After uniting to displace the Native Americans in a region, internal disputes over slavery were commonplace. The issue of slavery’s legality in newly-acquired territories would result in many political compromises, maintaining a tenuous peace through this time.

Undergirding all the expansions in economics, politics, and land was America’s expansion in religion and social conscientiousness. The Second Great Awakening swept through America with a with a belief in the “perfectibility of man” focused on correcting America’s societal ills, as well as the economy and government. The social reforms that swept through America (with varying degrees of success), such as abolition, women’s rights, the temperance movement, and reforms in public education – all find their roots in the Second Great Awakening.

From the era of Jefferson to the end of the Mexican-American War, America grew from a predominately agrarian society firmly located on the Atlantic seaboard to a nation sweeping the continent and leading the world in technological advancement. Belief in the ability and equality of the common man prompted Americans toward enterprise and invention, unleashing one of the greatest economy booms in world history. Yet, for all the advancements in politics and industry, America could not overcome the institution of slavery and societal conflicts. This mixture of expansion and compromise marks Period 4.

About the Author: Warren Hierl taught Advanced Placement U.S. History for twenty-eight years. He has conducted 250+ AP US History workshops for teachers. He was a member of the committee that wrote the original Advanced Placement Social Studies Vertical Teams Guide and the Advanced Placement U.S. History Teachers Guide. He has been a reader, a table leader, and, for the past eight years, the question leader on the DBQ at the AP U.S. History reading.

In other words- Mr. Hierl grades the essays you will write for the APUSH exam.