I'm adding some European firsts for me in DUB, EDI and BHD:
US total: 36 (I may have missed some but I can't remember other than these as of the time of posting)
The ones in bold are my frequent airports.
1. ATL Atlanta, GA
2. BOS Boston, MA
3. BTV Burlington, VT
4. CLT Charlotte, NC
5. CMH Columbus, OH
6. DCA - Washington, D.C. National/Reagan
7. DEN Denver, CO
8. DFW Dallas, TX Dallas/Fort Worth
9. DTW Detroit, MI - Metropolitan Wayne County
10. HNL Honolulu, HI
11. IAD Washington, D.C. - Dulles
12. IAH Houston, TX - Intercontinental/Bush
13. JFK New York, NY - Kennedy
14. LAS Las Vegas, NV
15. LAX Los Angeles, CA
16. LGA New York, NY - LaGuardia
17. MCO Orlando, FL - International
18. MDW Chicago, IL - Midway
19. MGW Morgantown, WV
20. MIA Miami, FL
21. MSP Minneapolis-St. Paul, MN
22. MSY New Orleans, LA
23. OGG Kahului, HI - Maui
24. OKC Oklahoma City, OK
25. ORD Chicago, IL OHare
26. PDX Portland, OR
27. PIT Pittsburgh, PA
28. RNO Reno, NV
29. SAN San Diego, CA
30. SEA Seattle, WA
31. SFO San Francisco, CA
32. SGF Springfield, MO
33. SJC San Jose, CA
34. SJU San Juan, PR
35. SNA Orange County, CA John Wayne
36. SLC - Salt Lake City, UT
Canada:
1. YYZ Toronto, ON Pearson
2. YUL Montreal, QC - Trudeau
Mexico:
1. CUN Cancun, QR
International total: 18
1. AMS Amsterdam, Netherlands
2. AUH Abu Dhabi, United Arab Emirates
3. BAH Manama, Bahrain
4. BRU Brussels, Belgium
5. DMM Dammam, Saudi Arabia
6. DOH Doha, Qatar
7. DXB Dubai, United Arab Emirates
8. FRA Frankfurt, Germany
9. IST Istanbul, Turkey
10. KWI Kuwait City, Kuwait
11. LCA Larnaca, Cyprus
12. LHR London, England, United Kingdom - Heathrow
13. MLA Valletta, Malta
14. PRG Prague, Czech Republic
15. RUH Riyadh, Saudi Arabia
16. DUB Dublin, Ireland
17. EDI Edinburgh, Scotland, United Kingdom
18. BHD Belfast, Northern Ireland, United Kingdom - City/George Best