What was the free soil position? Where was it the strongest in the United States

A single-issue party, its main purpose was to oppose the expansion of slavery into the Western territories, arguing that free men on free soil constituted a morally and economically superior system to slavery.

Explanation:

At a convention in Buffalo, New York on August 9, 1848, more than 10,000 men from all the northern states and thee border states met in a huge tent in a city park. The resulting Free Soil Party was built on a coalition of four elements: the previous Liberty Party, Free-Soil Democrats, Barn-burners, and Conscience Whigs