A disturbing increase in early-onset colorectal cancer (EOCRC) has prompted recent guidelines to recommend lowering the CRC screening starting age from 50 to 45 years old for average risk individuals. Little is known about the prevalence of colorectal neoplasia in individuals between 45-49 years old, or even younger, in the United States. We analyzed a large, nationally representative dataset of almost 3 million outpatient colonoscopies to determine the prevalence of, and risk factors for, colorectal neoplasia among patients aged 18-54.