The belt is 6-feet long and contains ten thousand beads. It depicts a house in the middle, representing the Six Nations. The Mohawk are the keepers of the eastern door and the Seneca the keepers of the western door. They are holding hands with 13 others, representing the 13 United States. (The historian I'm currently reading as well as the Onondaga website say they represent 13 states, but Kentucky and Vermont were already admitted to the union)
The wampum symbolizes friendship with the Six Nations Iroquois and is a visual representation of the Treaty of Canandaigua. This treaty is commemorated annually on November 11, where U.S. officials distribute cloth to fulfill the terms of the treaty.
(This is very random, but I just learned about this today, so I thought I'd share)
Edit: In my haste to share, I initially linked to a recreation of the belt instead of the original. Thank you /u/Tipofmywhip for bringing up how clean it looked. I still think the original looks pretty good, though.
Source: reddit post