No studies using national data have evaluated changes in nonfatal dog bite injuries among children, adolescents, and young adults during the past 2 decades. We examined estimates of annual nonfatal dog bite injuries among persons aged 0-19 treated in US emergency departments (EDs) from 2001 through 2017. We examined data from the Web-based Injury Statistics Query and Reporting System to compare estimates of the annual rates of nonfatal dog bite injuries in EDs among all persons aged 0-19, by age group (0-4, 5-9, 10-14, and 15-19), and by sex. We determined significance by comparing 95% confidence intervals (CIs), and we standardized rate calculations to the year 2000 population. During 2001-2017, an estimated 2 406 109 (95% CI, 2 102 643-2 709 573) persons aged 0-19 were treated in EDs for nonfatal dog bite injuries (age-adjusted rate of 173.1 per 100 000 persons aged 0-19). The estimated number of nonfatal dog bite injuries declined significantly, from 181 090 (95% CI, 158 315-203 864) in 2001 to 118 800 (95% CI, 97 933-139 667) in 2017. The highest rate was among children aged 5-9. Male children, adolescents, and young adults were significantly more likely than female children, adolescents, and young adults to be treated in the ED for nonfatal dog bite injuries, driven by male-female differences in children and adolescents aged 5-14. Although the estimated number of nonfatal dog bite injuries among persons aged 0-19 declined significantly in the past 2 decades, additional regulatory and educational efforts specific to age and sex may lead to further reductions in nonfatal dog bite injuries.