Replies

PeaBrain first quoting: "# 571 again. Brojoke canard...
'Further, the original Morrill proposals were quite modest, raising average rates from circa 15% to 20%, still relatively low compared to historical numbers.' "

PeaBrain responding to quote: "BS again.
From the day of its origin, Morrill rates were very high.
The bill proposed raising the taxation rate from an average of approximately 37.5% with a greatly expanded list of covered items..."

This source shows that average pre-Morrill tariffs in 1860 were 15%.

This source, as well as others I've seen says of the original Morrill tariff bill:

"In general, the tariff increased duties 20 percent on certain manufactured goods and 10 percent on specified raw materials.
The bill reflected the Republican Party’s commitment to general economic growth and expressed its belief that business interests interacted harmoniously and positively in the economy.

"The tariff also differed in that it distributed the burden of protection across society rather than placing it on specific regions or poorer classes....
The bill placed a 10 percent duty on goods considered necessities and a 20 percent impost on products that were less necessary.
Congress authorized a 30 percent tax on luxury items based on their value..."

PeaBrain: "Your comment about 'the wisdom of Congress' raising the rates after secession is flat out BS again."

This source says about the First Morrill tariff:

"In fact, the Tariff proved to be too low for the revenue needs of the Civil War, and was quickly supplanted by the Second Morrill Tariff, or Revenue Act of 1861, later that fall.[12]"

Finally, this source disagrees with the above, and more closely agrees with you, PeaBrain, but I think some of the explanation is: comparing the original Morrill proposal of 1859, in the face of Southern opposition, with the final Morrill Act of 1861 given the new Republican majorities.

Your source that you quoted says this: “In general, the tariff increased duties 20 percent on certain manufactured goods and 10 percent on specified raw materials.”

That is factually misleading. First from U.S. Tariff Rates - Ratio of Import Duties to Values: 1821-1996.

"In its first year of operation, the Morrill Tariff increased the effective rate collected on dutiable imports by approximately 70%. In 1860 American tariff rates were among the lowest in the world and also at historical lows by 19th century standards, the average rate for 1857 through 1860 being around 17% overall (ad valorem), or 21% on dutiable items only. The Morrill Tariff immediately raised these averages to about 26% overall or 36% on dutiable items,

Here from Taussig and Adams:

“The bill immediately raised the average tariff rate from about 15 percent (according to Frank Taussig in Tariff History of the United States) to 37.5 percent, but with a greatly expanded list of covered items. The tax burden tripled.”