Of course, you do, maybe not Delta? I guess enforcement can be discretionary, and you may have a frequent flyer status that supercedes, but here are the rules posted by Delta (and similar to others, I am told, although I fly 90% Delta coming from Atlanta);
Oversize Baggage
One-way Fees for Oversized Baggage
The following charges apply if your checked bag exceeds our size limitations:
United States
Geographic Region Ticket Purchase Date Fees (Each Way)
Travel within/between United States, Canada, Puerto Rico, U.S. Virgin Islands Any 175 USD/CAD/EUR* for bags measuring 63–80 inches (161-203 cm) in combined length, width, and height
300 USD/CAD/EUR* for bags measuring 81-115 inches (204-292 cm) in combined length, width, and height
Bags larger than 115 inches (292 cm) are not allowed
36 + 15 + 16= 67" combined.