Shouldn't Puerto Rico be under the US?

I thought they were represented by the USTA/us.Can someone explain to me.

Puerto Rico is a self governing commonwealth associated with the US, for that reason has some independence for many subjects as the sport representation etc. is not a part of the US at least not completely
you can obtain more info just clicking this link:
puerto rico (http://plasma.nationalgeographic.com/mapmachine/index.html?id=362&size=medium&left=-67.27&bottom=17.92&right=-65.3&top=18.52)

Thanks.

Thanks for the info, I though like you Maccardel.