Ontario has been given to about 877 people in the United States since 1880. It was most common in 1991, which makes it a Gen X and millennial name.
Its best year was 1991, when 35 babies were given the name, ranking 2127th. The typical living American called Ontario is about 33 years old today.
Source: US Social Security Administration, national and state name files, 2025 release. Etymology researched and written by our editors. Living-population and median-age figures are our own estimates, described in the methodology.