I MISSOURI 1 
Arctic zone 
Hudsonian 
Boreal 
Region 
' [Transition IsfizaiVe v H c - -Sm rW 
Region I Upper Austral "" I 
(^Lower Austral T ~™~ 
Tropical/" . ' ^ 
Region ( Tr °P ,cal 
ZONE MAP OF iYORTH AMERICA 
Beproduced by permission of the United States 
department of Agriculture from the Fourth 
Pro.ls.onal Map of the Biological Survey, by 
C. HartMerriam. Yeraon Bailey. E.W. Nelson 
Gulf of 
Campeche 
iTRAI7 
SlERICfV 
10o°Longitiule 100- 
90° Greenwich 
