What led to the forming of the know-nothing party?

The Know-Nothing party (aka the Whigs) formed because they didn't like Jackson or his policies. They formed after the Hartford convention (after which, the Federalist party f … ell apart). The Whigs wanted the opposite of the Jacksonian Democrats at this time.

More Details down there

The Native American Party, renamed the American Party in 1855 and commonly known as the Know Nothing movement, was an American nativist political party that operated nationally in the mid-1850s. It was primarily anti-Catholic, xenophobic, and hostile to immigration, starting originally as a secret society. The movement briefly emerged as a major political party in the form of the American Party. Adherents to the movement were to reply "I know nothing" when asked about its specifics by outsiders, thus providing the group with its common name.

couples could only have one child to reduce the population growth.

yellow fever and other tropical diseases