If you have a site that is not exclusive to visitors from the USA you might want to write "United States of America" instead. And "US Congress" (I guess). America is two continents.

Good call. Done!

Nice work, Chris! I particularly like your embedded calling functionality. Where did you get it from?

If anyone's looking something a bit more configurable, https://wordpress.org/extend/plugins/sopa-blackout-plugin/ is another option. Disclaimer: I was involved in the creation of this plugin, along with Site5 and Ten-321.

Would the login page also be affected by this plugin? If so, how would an admin login if he isn't already?

Nope, it won't. `wp-login.php` is a static file (no URL rewriting), so your server should serve it up directly. Also, the plugin only includes the hooks/functions that do all the work when you aren't in the admin area.