they are only 50 States in the US, the best way to remember this is Hawaii Five-O the TV show, im not saying thats why the TV show was call such, I'm just saying that Hawaii Five-O sounds like Hawaii 50, as Hawaii is the 50th state in America, and is called Hawaii, the Aloha State and was classed as a state on August 21, 1959
Also there are 50 Stars on the US flag one each representing the 50 states of the United Stats of America and consists of thirteen equal horizontal stripes of red (top and bottom) alternating with white. the 13 stripes represent the thirteen colonies that rebelled against the British monarchy and became the first states in the Union.
Puerto Rico is still not classed as a state, they have voted for Puerto Rico to become a state 3 times in 1967, 1993 and 1998, and they have always decided against it. So for now, Puerto Rico remains a commonwealth associated with the United States.
As a side note "Independence Day" is celibrated because of the 13 colonies rebelled against the British monarchy on the 2nd july 1776, there are sompeople that think this date is wrong as the 4th of July was when the Declaration of Independence was signed, but alas it may have even been sign nearly a month after on August 2, 1776, and not on July 4 as is commonly believed, but this is still up for debate and I'm not trying to prove otherwise.
Hope this helps
