229 



Figure IV.4.15 



ATTENDANCE AT MAJOR TYPES OF OUTDOOR 

 RECREATION AREAS 



Visits in millions 

 400 



300 

 200 



100 

 80 



60 

 40 



20 



10 

 8 



6 

 4 



I 



a8 



0.6 

 0.4 



0.2 



1910 



1920 



1930 



I960 1965 



Source: Morion Clowson and JocK L. Kultsch, Economics of Outdoor Recreation (Baltimore: 

 John Hopkins Press, 1966), P. 44. 



