wilderness - 12:24 pm on Apr 6, 2012 (gmt 0)

But then, if you are interested only in North American readers, then why not merely check the country code through Apache or .htaccess and ban by country?

DeeCee,
I had active websites for more than a decade, and with these same restrictions.
The global denial was initiated long before any Geo-IP info existed.
I already have the numbers in place and really don't have any need to consult another source. Very rarely do I find a new or reassigned IP range to add outside of North America.

Banning by individual countries (i. e., Geo IP) requires condensing the combined lines of non-desired countries into lesser lines.
I don't know if you've ever attempted anything like this manually (I did in 2002 when I separated the Oceanic ranges from the other APNIC ranges), however I can assure that it's just short of a nightmare.