The Georgia document mentions the Walker Tariff of 1846, named for its sponsor, Secretary of Treasury of Robert J Walker of Mississippi. The Walker Tariff reduced rates from 32% to 25%. The Tariff of 1857 set rates even lower in response to a decline in demand for American manufactured goods in European markets. Higher rates were not enacted until Southern states seceeded and left their seats in Congress vacant.

Since direct taxation did not yet exist, the tariff represented a major source of revenue for the Federal government. For that reason many Southern leaders supported higher (well above 20%) tariff rates. When the tariff was set too low, as it was from time to time, the U.S. Treasury risked bankruptcy.

Are we to suppose that the mere existence of interest groups in the North (and the South) which favored a higher tariff led to secession? I've read dozens of newspapers from the 1859-1860 period printed in Alabama and have not seen a word about tariff rates or tariff legislation, good or bad.

In 1857 lower tariff rates were advocated in the South, in the North and the West --
http://en.wikipedia.org/wiki/Tariff_of_1857