Neva Morris died at a nursing home in Ames at about 4 a.m. Tuesday.
The Gerontology Research Group in Los Angeles says the oldest person in the U.S. is now Eunice Sanborn of Jacksonville, Texas.
She is 113 years and 260 days. The oldest person in the world is Japan's Kama Chinen at age 114 years, 330 days. Neva Morris' family says in a statement that she led a "long, charitable and wonderful life."
Only one of her four children, a son in Sioux City, Iowa, is still alive.
Morris became the oldest living American on March 8, when a 114-year-old New Hampshire woman died.