This is weird, I am the operator of that Tor Exit relay. The relay is indeed hosted in the United States, perhaps the geoip is wrong. You can confirm this by running a traceroute to the IP and following the hops. It ends in Dallas, Texas.
Changing to a more recent version of TOR(>= 4.5) allows for specific exit node selection. The issue may have been caused by high latency; in the previous versions of TOR circuits with a certain delay may have been disabled.
Perhaps you might get a better answer if you explain; Why you want to use multiple IP's simultaneously? or Why you want all the nodes related to your use of Tor to be in the US?
While you might know this already.
If you have the Tor Browser running, and want to change to a different IP, you would click on the green onion and specify new identity, although ...
Your email provider uses a so-called GeoIP database. In this list are IP addresses and their probable location saved. But Maxmind for instance tries to find out if an IP address is an anonymizer. Those IP get no specific country, but an A1. Thatswhy you probably see A1 everytime you log in via Tor.