20. Happy Can Portable Toilets, Atlanta, GA
19. Drop Zone Portable Service Inc., Frankfort, Ill.
18. Blackman's Best Seat In The House Inc., Bradley, Ill.
17. Plop Jon Inc., Port Saint Lucie, Fla.
16. A.S.A.P. Port-A-Pots Inc., Hampstead, Md.
15. Ameri-Can Engineering, Argos, Ind.
14. Bobby’s Pottys, White Marsh, Md.
13. Johnny On The Spot Inc., Old Bridge, N.J.
12. LepreCAN Portable Restrooms, Chicago
11. Loader-Up, Inc., Sarasota, Fla.
10. Mister Bob’s Portable Toilets, Vero Beach, Fla.
9. Royal Throne, Allentown, PA
8. Tanks Alot, Tomball, Tex.
7. Tee Pee Inc., Roseville, Mich.
6. Wizards of Ooze Ltd., Anacortes, Wash.
5. Oui Oui Enterprises Ltd., Chicago
4. Gotta Go Potties, Stroudsburg, Pa.
3. UrinBiz.com, Chicago (apparently changed their name or went out of business)
2. Willy Make It? Oregon City, Oregon
1. Doodie Calls, New Orleans
Just to make sure, I looked all of these up for your convenience. Kirby Barlett-Sloan also submitted Tardis Portable Toilets. And D. Webb told us about Nix Tank Company, which has the slogan "A royal flush beats a full house!"