In 1844, the U.S. population reached 19.6 million people, an increase from 1840 of nearly 2.4 million people. Amazingly, four years later, the national population increased another 2 million, reaching 22 million (a 13-percent increase). Four new states came into the union between the time of Polk's election and the end of his term: Florida (1845), Texas (1845), Iowa (1846), and Wisconsin (1848). This kept the balance at exactly fifteen slave states and fifteen free states, although the status of California and New Mexico remained undecided when Polk left office.

These 4.4 million new Americans—of which 1.5 million were immigrants, mainly from Germany and Ireland—entered a country that was highly partisan and increasingly sectional in its politics. In 1840, nearly 2.8 million people had voted, or an astounding 80.2 percent of the eligible voters, up from 57 percent in 1836. This remarkable rate held in 1844 at 78.9 percent of eligible voters and remained in the high seventies for the remainder of the century. Obviously, the 2.7 million voters in 1844 held firm to the 1840 party lines. Indeed, if Clay had not lost votes in New York to the Liberty Party candidate, James G. Birney, he would have won the popular vote and the Electoral College vote as well.

Suffrage, Prosperity, and the New Classes

Along with this growth came immense economic changes that in turn drove politics and encouraged partisanship. The richest man in America in 1845, for example, was John Jacob Astor, who held a fortune worth $25 million. On the other hand, due to industrialization, squalid working class slums began to appear in every American city, principally filled with Irish and German immigrants as well as free black men and women. By 1845, the top 1 percent of wealthiest people in New York City held 50 percent of the total wealth, an increase of 10 percent since 1828. And the cities were larger: Philadelphia stood at 389,000 in 1850; New York was twice as large. Mortality rates in these two cities were exceedingly high, and a slave born in the 1840s could on average expect to live longer than a person born in New York or Philadelphia. About 70 percent of the people who lived in these cities were poor, with annual incomes of $100 or less. Another 25 to 30 percent were middle class, with yearly incomes between $100 and $5,000. Only 3 percent earned more than $5,000 each year. Those Americans who chose to remain in the countryside and grow cash crops rather than seek their financial prosperity in the city could expect to be healthier and to live longer.

In an appeal to tenant farmers, craftsmen, and adult males living in white households, Jacksonian Democrats had worked in the 1820s and 1830s to widen the franchise beyond property owners in order to include all adult white males. But they failed to anticipate this new urban class of unskilled workers and the influx of immigrants. Now even Democrats were nervous about just how broad the franchise had become, but they did a better job than Whigs in garnering the votes of immigrants and factory workers. Those who prospered in the cities amid the changing economy tended to vote Whig and those who did not tended to vote Democrat.

Era of Reform

Although no women were allowed to vote in any state in the 1840s, many were involved in political activism through Christian reform movements. Nearly every church in the nation had charity groups staffed and run largely by women. The spread of public education in the North and West was accompanied by droves of women teachers in a field previously dominated by men. By 1850, women staffed most of the primary teaching positions in the nation's expanding roster of public and private elementary schools. Thousands of women joined Martha Washington Temperance Reform Societies, campaigning to end the drinking of hard liquor, which had peaked at an average of seven gallons per person in 1836. This was an offshoot of the Washington Temperance Society, a working class competitor to Lyman Beecher's American Temperance Society. By 1850, the consumption rate had decreased by half. Numerous other women joined the Female Moral Reform Society, which worked to eliminate prostitution by organizing charity and work opportunities for poor women and orphans. Others in the 1840s campaigned to reform the horrible conditions of the nation's insane asylums, orphanages, and prisons.

Some Americans, concluding that culture mattered more than politics, embraced utopian communities and new religions as alternatives to political activism. Groups such as the Millerites, the Shakers, the Oneida Community, and socialist communities appealed to thousands of men and women. Roman Catholics founded many new convents and monasteries during this time period as well, and in response anti-Catholicism in a variety of forms became a major movement of its own under the leadership of Lyman Beecher and Samuel F. B. Morse. Besides defamatory literature, this included the burning of an Ursuline convent and school outside Boston in 1834 and a series of deadly riots against Irish Catholics in Philadelphia in 1844. But no new religious movement was more successful, and more attacked, than the one founded by Joseph Smith. In 1830 Smith published the Book of Mormon, a text about ancient North America that he claimed to have discovered in New York state and then translated from an ancient Egyptian dialect. Smith called his new religion the Church of Jesus Christ of Latter-day Saints but most Americans nicknamed it Mormonism. Mormonism blended an extraordinary communitarianism with hard work and selfless cooperation, enabling the group to prosper and grow in numbers. The Mormons' success, and the unique features of its religion, which included polygamy, aroused the wrath of non-Mormon neighbors, who believed that the group was un-American and anti-individualist. The Mormons were forced to flee from their homes in New York and Ohio to Illinois, where a mob killed Smith. After dissension split the community, the bulk moved on to the Great Salt Lake region of present-day Utah, located in the northernmost part of the Mexican Cession.

Women's Political Voice

Thousands of women worked in the forefront of the abolitionist movement in the 1840s, canvassing their neighborhoods in petition drives requesting the abolition of the slave trade in the District of Columbia. When the abolitionist movement split in 1840 into those that advocated forming a new political party to run abolitionist candidates for office and those that continued to insist on moral suasion alone, female adherents also followed suit.

Most women activists discovered, however, that while they were valued to do much of the legwork, there were few opportunities for them to lead or to speak out as women. The few who did, such as Sojourner Truth and the Grimke sisters, were criticized at every turn, frequently by fellow male reformers. The women were told that their best contributions could be made in ways reflecting the popular notion of separate spheres for men and women—the public world for men and the private world of the home and family for women. Empowered by their own sense of accomplishment as reformers, a group of women (led by Elizabeth Cady Stanton and Lucretia Mott) organized the Seneca Falls Convention of 1848 in upstate New York to focus specifically on women's rights. The Convention's Declaration of Sentiments, a document modeled on the Declaration of Independence and infused with a then-new Marxist interpretation of history as a conflict of classes, began by asserting, "We hold these truths to be self-evident: That all men and women are created equal." It went on to state, "The history of mankind is a history of repeated injuries and usurpations on the part of man toward woman, having in direct object the establishment of an absolute tyranny over her." After documenting this "tyranny," the Declaration called for women's suffrage as the best means for women to protect themselves and to realize their potential as humans equal to men.