| Zone 1 |
Northwestern Zone of North America |
| Zone 2 |
Northeastern Zone of North America |
| Zone 3 |
Western Zone of North America |
| Zone 4 |
Central Zone of North America |
| Zone 5 |
Eastern Zone of North America |
| Zone 6 |
Southern Zone of North America |
| Zone 7 |
Central American Zone |
| Zone 8 |
West Indies Zone |
| Zone 9 |
Northern Zone of South America |
| Zone 10 |
Western Zone of South America |
| Zone 11 |
Central Zone of South America |
| Zone 12 |
Southwest Zone of South America |
| Zone 13 |
Southeast Zone of South America |
| Zone 14 |
Western Zone of Europe |
| Zone 15 |
Central European Zone |
| Zone 16 |
Eastern Zone of Europe |
| Zone 17 |
Western Zone of Siberia |
| Zone 18 |
Central Siberian Zone |
| Zone 19 |
Eastern Siberian Zone |
| Zone 20 |
Balkan Zone |
