ISO 3166-2 geocode for Argentina. This is used as an international standard for shipping to Argentina. Each Argentinian province has its own code with the prefix AR.. For example, the code for the Province of Buenos Aires is ISO 3166-2:AR-B.
The USB 2.0 interface can be a limit due to signalling and command overhead as well as spacing between packets. I have a fast SSD connected by USB 2.0. The drive is much faster than the interface (by more a factor of 10). Read Speed maxes out around 33 MB/s and Write Speed at 17.5 MB/s. Write Speeds are almost 50% slower due to a verify-read after the write and the fact that the USB signal is half-duplex as another answer mentions.
SanDisk Ultra cards--particularly those with the newer 3.0 specification--can read data up to 15 megabytes per second. The writing speed is somewhat slower at an average write speed of 10 megabytes per second.