Name one of the two longest rivers in the United States.

Why this is the answer

The official list accepts two rivers here, the Missouri and the Mississippi, and the question only asks for one. The Mississippi counts, but the USCIS lesson points out that the Missouri is actually the longer of the pair. It rises in Montana and empties into the Mississippi, so the two work as one connected system more than as rivals. The 2025 USCIS textbook shows how that system sits on the map. The Mississippi runs north to south through the middle of the country, and the Missouri crosses several western states before joining it. The same page places the country's two large mountain ranges, the Rockies in the West and the Appalachians in the East. The Mississippi passes through ten states, and before Europeans arrived, American Indians used it for trade, food and water. Its nickname is the Father of Waters, and today it is a major shipping route and a source of drinking water for millions. The Missouri earned the nickname Big Muddy from all the silt it carries. The first Europeans to find it were the French explorers Jolliet and Marquette, in 1673. The rivers also anchor a piece of history that comes up elsewhere on the test. In 1803 the United States bought the Louisiana Territory from France, a vast stretch of land between the Mississippi River and the Rocky Mountains. France was willing to sell because it needed money for the wars it was fighting in Europe. A famous river that is not on the list, such as the Colorado, the Hudson or the Rio Grande, earns no credit. The Hudson is the sneakiest, because it does appear as an accepted answer to a different question, the one about where the Statue of Liberty stands. Here it does not count. If your mind goes blank, think of two rivers that both start with M and meet in the middle of the country.