When staffers come up with a new design for a balloon, they first mold it in clay. Then, to help them calculate how much helium it would take to fill the design, they use good old water displacement.
The average balloon requires 12,000 cubic feet of helium. That's enough to fill about 2,500 bathtubs.
The average balloon requires 90 handlers during the parade. Handlers must weigh at least 120 pounds and have no heart, back, or knee problems.
The balloons were originally made of rubber. Now, they're made of fabrics coated in a polyurethane material that's flexible, durable, and leak-resistant. Polyurethanes are synthetic plastic materials that also commonly show up in couch cushions, insulation, and even in synthetic-fiber clothes.