If you check the State & County QuickFacts page on the U.S. Census Bureau website, you'll see that the land area of Minnesota is 79,610 square miles and the land area of Iowa is 55,869 square miles. According to this source, the land area of Minnesota is significantly larger than that of Iowa. This source is clearly organized and provides a consistent format for each state. Once you have found the figure for one state, you can easily find it for another.
The website of the Population Division of the U.S. Census Bureau shows that the area of Minnesota is 79,617 square miles and that of Iowa is 55,875 square miles. According to this source, Minnesota is nearly 24,000 square miles larger than Iowa. The advantage of this site is that you can find all the relevant information on one page. The major disadvantage of this site is that it is somewhat dated (last updated in 2000), although state borders don't usually change.
According to the official state website of Minnesota, the area of Minnesota is 86,943 square miles, including 4,780 square miles of inland water, meaning that there are 82,163 square miles of land. According to the official state website of Iowa, the area of Iowa is 56,275 square miles. That figure includes 310 square miles of inland water, meaning that there are 55,965 square miles of land. The major disadvantage of this approach is that each state's website has a different format and layout, and you can spend a considerable amount of time searching for the desired information.
You can also consult a standard, nongovernmental reference source. According to the Infoplease website, Minnesota has a land area of 79,610 square miles, a water area of 7,329 square miles and a total area of 86,939 square miles. According to the same site, Iowa has a land area of 55,869 square miles, a water area of 402 square miles and a total area of 56,272 square miles. This site has two big advantages: All of the relevant information is on one page, and there is a helpful breakdown by land area, water area and total area.
