Oregon has lots of ants. Why aren't there any anteaters (or aardvarks)?
Anteaters and aardvarks are fascinating animals! What's really amazing is that they are two completely unrelated families adapted to eating very similar types of foods.
Aardvarks only occur in (southern) parts of the African continent, so they haven't had access to our continent.
There are 4 species of anteaters that live in countries of Central and South America. Mostly they inhabit dense forest or range with lots of streams and superabundant populations of both ants and termites. Most important to your question however is that South and North American species evolved before the south and north parts of our current continent got land-bridged together. Only a few south American species successfully pioneered into North America, such as opossum.
We have other animals from a variety of taxa (birds, reptiles, small mammals, some herptiles, and fish-if they're lucky) that eat ants.