The Mellon Family – $11.5 Billion

You can trace the Mellon family back to its roots in Pittsburgh, Pennsylvania, where a university and several museums bear their name to this very day. Back in 1869, the family decided to found Mellon Bank. While their wealth started right there, it skyrocketed when they decided to invest in Gulf Oil, which later became Chevron-Texaco.

The Mellons are also known for their philanthropic ventures. You see, they founded Washington D.C.’s National Gallery of Art. What’s more, the family actually originates from Ireland thanks to its original patriarch, Thomas Mellon. Furthermore, he was the son of two Scottish-Irish farmers. Now, they own what has effectively become a massive empire!