Firefox > Use Switch Proxy Addon IE > Properties > Internet Options > Lan Settings > Use Proxy > Place Proxy xx.xxx.xxx.xx : xxxx in the port Done amen.
http://www.ip2location.com/free.asp You can check here by placing IP's. USA proxy List http://www.aliveproxy.com/us-proxy-list/ While Google http://www.google.com.pk/search?hl=en&q=US+Proxy+list&btnG=Google+Search&meta= ~