What event significantly increased American nationalism in the early 19th century?

The conclusion of the War of 1812 significantly increased American nationalism in the early 19th century as it fostered a sense of unity and pride among Americans. The war, often referred to as the "Second War of Independence," ended in a stalemate, yet it was perceived as a victory for the United States since it reinforced the country's sovereignty and independence from British influence. The successful defense against British forces, particularly in notable battles such as the Battle of New Orleans, helped to instill a sense of national identity and purpose.

Additionally, the war led to the demise of the Federalist Party, which had opposed the conflict, and allowed the Democratic-Republican Party to dominate American politics. This political shift further unified the nation under a common ideology, promoting national unity and pride. The post-war period also saw an upsurge in patriotic sentiments, expressed through art, literature, and the development of symbols like the national anthem, which collectively contributed to a burgeoning sense of American nationalism.

In contrast, the other events listed did have significant effects on the nation, but they did not catalyze an immediate and widespread surge in nationalism comparable to the direct consequences of the War of 1812. The signing of the Constitution established the framework