In August 1848 at Buffalo, New York, a meeting of anti-slavery members of the Whig Party and the Liberty Party established the Free-Soil Party. The new party opposed the extension of slavery into the western territories. The main slogan of the party was "free soil, free speech, free labour, and free men".

In the 1848 presidential election, Martin Van Buren, the party's candidate, polled 10 per cent of the vote. He split the traditional Democratic support and enabled the Whig candidate, Zachary Taylor, to win.

By 1852 the Free-Soil Party had 12 congressmen but in presidential election, John P. Hale won over 5 per cent of the vote. Two years later, remaining members joined the Republican Party.