[cbr]

> I'd get 3-5% higher CPM if I filtered non-US traffic.

3-5% higher CPM on how many fewer pageviews? In general, filtering out traffic should always make you less money, even as filtering to the most profitable traffic increases how much you make per page view.

If non-US traffic really were losing you money your advertising company could always drop ad requests from non-US traffic.

[reaperducer]

Non-US traffic is essentially non-revenue for many American web sites (unless you're running AdSense). Serving pages still costs money, though. So it makes more sense to block non-US traffic than to serve it ad-free.