Why are there so many people from Puerto Rico with the surname Rivera?

Question:

Why are there so many people from Puerto Rico with the surname Rivera?

This is my maiden surname. My family is of Spanish descent from Northern New Mexico and whenever I try to trace my ancestry I find so many Rivera's in Puerto Rico. I'm just curious to see if anyone might know the reason for this.

Best Answer - Chosen by Asker: Puerto Rico was invaded by Spain in Nov 19, 1493 and was occupied by the Spaniards 'till July 25, 1898. So not only did we receive from Spain their religion, architecture influence and language but we also got their surnames. Rivera means "by the shores of the sea or river". There were many elite families with the surname Rivera in the 1700's. Puerto Rico was a great way to invest money so many of these families traveled here. Of course the slave trade was at it's high and the slaves were given their owners' surname. Needless to say prominent Families like Rivera and Gonzalez left their heritage in Puerto Rico more than others. By the way my name is Efrain Rivera.