From the Iowa Legislature homepage:

In 1917, friends of Senator William B. Allison, citizens and school children of Iowa, and the state legislature raised this memorial. A pivotal figure in Iowa's Republican party, Allison (1829-1908) represented Iowa in Congress for 43 years. He was twice a candidate for the presidential nomination of his party and was a close associate of every United States president from Abraham Lincoln to Theodore Roosevelt. Evelyn B. Longman of New York designed the monument. A central plaque picturing Allison is flanked by symbols of "Knowledge," "Legislature," and "Financial Prosperity" on the left, and "Peace," "Humanity," and "Agricultural Prosperity" on the right. The topmost figure, symbolizes "The Republic."

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