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 to 1860 being around 17% overall ("ad valorem"), 21% on dutiable items only. The Morrill Tariff immediately raised those averages to about 26% overall, or 36% on dutiable items. Further increases by 1865 left the comparable rates at 38% and 48%. Although higher than in the immediate antebellum period, the new rates were still significantly lower than between 1825 and 1830, when rates had sometimes been over 50%.