California · United States
Ontario population
171,214people · latest figure
Ontario has a population of 171,214, making it the 155th largest place we list in United States. It is in California.
Ontario holds under a tenth of one per cent of United States's 349,035,494 people. New York City, the largest place we list there, is 51 times its size. Twenty years earlier the World Gazetteer recorded 172,808, almost unchanged.
The 2005 figure comes from the World Gazetteer archive restored on this site. The two sources may draw the settlement's boundary differently, so treat the change as indicative rather than exact. Why figures differ.
Ontario is in California, which has 1,132 recorded places.
Nearby in size
| Place | Region | Population |
|---|---|---|
| Rancho Cucamonga | California | 175,236 |
| Cape Coral | Florida | 175,229 |
| Sioux Falls | South Dakota | 171,544 |
| Fort Collins | Colorado | 170,924 |
| Springfield | Missouri | 170,188 |
| Elk Grove | California | 166,913 |
All places in United States → · California →
Figures are the latest available in GeoNames (CC BY 4.0), which draws on national censuses of varying dates — treat them as recent, not same-year. Country totals are UN World Population Prospects 2024 (medium variant) where the UN lists the country separately; the handful it reports under a parent state keep a GeoNames figure and are marked as such. Sources & method.