It was originally started in 1986 by President Ronald Reagan and included a collaboration between such groups as American Mathematical Society, American Statistical Association, Mathematical Association of America and Society of Industrial Applied Mathematics.
Wow, can you imagine the wild and crazy parties these guys would throw. I bet the month comes to a crescendo with a rousing chess tournament followed by all-you-can-eat bran muffins. The goal is to support and bring notice to the field of mathematics and how it is used in society. It's not just for the high level math learned by professional, but the everyday math that people use to balance their checkbooks.