FUTURE DEMAND FOR TIMBER 



359 



Table 195. — Population oj the United States at 

 beginning and end of specified periods with aver- 

 age annual rate oj increase, and Census Bureau 

 projections 1956 to 1975 with implied rates of 

 increase 



Table 196. — Female reproduction rates ^ in the 

 United States, specified periods and years, 1905-54 



IDAUOHTERS PER 1,000 FEMALES] 





Population ' 



Average 



Item and period 



At begin- 

 ning of 

 period 



At end 

 of the 

 period 



annual 



rate of 



increase ^ 



Census enumerations: 

 1800-50 



Million 



persons 



5.3 



23. 2 



76. 1 



123. 2 



132. 1 



151. 7 



165. 3 

 165. 3 

 165. 3 

 165. 3 



Million 



persons 



23.2 



76. 1 



123.2 



132. 1 



151. 7 



165. 3 



228.5 

 221. 5 

 214. 6 

 206. 9 



Percent 

 2. 99 



1850-1900 



1900-30 - -- 



2. 40 



1. 62 



1930-40 --- 



. 79 



1940-50 . . 



1. 39 



Census estimates,' 1950- 

 55 



Census projections,^ 

 1955-75: 



Series A A 



Series A 



1. 74 



1.63 

 1. 47 



Series B 



1. 31 



Series C 



1. 13 







1 Census Bureau's estimates of the July 1 population 

 from 1900 onward. 



2 Computed from figures in thousands before rounding. 



3 Bureau of the Census. Provisional Estimates of the Popu- 

 lation of the United States. Current Population Rpts. Ser. 

 P-25. Aug. 1956. 



* Bureau of the Census. Revised Projections of the Popu- 

 lation of the United States, 1960 to 1975. Current Popula- 

 tion Rpts. Ser. P-25, No. 123. Oct. 1955. 



of her reproductive period of life would be ex- 

 pected on the average to bear 1.654 daughters 

 and about 1.679 sons *** — a total of 3.333 children. 

 Assuming that 15 percent for one reason or 

 another do not bear children, the average for the 

 remaining 85 percent of the female population 

 would be 3.921 or slightly less than four children. 

 Families of that average size, in an economy of 

 high-level employment, do not appear to be be- 

 yond the re ilm of reasonable probability. 



With more pensions and other forms of old-age 

 security, the senior members of the population 

 will be less dependent on their adult offspring 

 than they have been in the past. That will tend 

 to increase the income which young and middle- 

 age families will have for support of children. 

 These lines of reasoning tend to show that the 

 upper population projections are not at all 

 improbable. 



The lower series are, of course, contingent on 

 falling fertility rates. Whether or not low rates 

 in the past have been a consequence of economic 

 depression, there certainly is some justification 



»» About 100.0 males are born for every 98.5 females. 



Year or 



Gross 



Net 



Year 



Gross 



Net 



period 



rate 



rate 





rate 



rate 



1905-10- _ 



1,793 



1,336 



1945 



1,212 



1, 132 



1921-25- _ _ 



1,318 



1, 104 



1946 



1,430 



1,344 



1926-30--- 



1, 168 



1,004 



1947 



1,593 



1, 505 



1930-35--- 



1, 108 



984 



1948 



1,514 



1,435 



1935-40.-- 



1, 101 



978 



1949 



1,515 



1,439 



1940 



1, 121 



1,027 



1950 



1,505 



1,435 



1941 



1, 168 



1,075 



1951 



1, 591 



1, 519 



1942 



1,277 



1,185 



1952 



1,635 



1,561 



1943 



1,323 



1, 228 



1953 



1, 665 



1, 594 



1944 



1, 249 



1, 163 



1954 



1, 723 



1, 654 



' See text footnotes 66 and 67 for definition of gross and 

 net reproduction rates. 



Source: Statistical Abstract of the United States, 1956, and 

 Vital Statistics of the United States, 1954. Net rates for 

 1921-25 and 1926-30 estimated on basis of reported gross 

 rate. 



for the belief that marriages were postponed 

 during the 1930's and that married couples post- 

 poned having as many children as they would 

 have desired. This is probably one of the im- 

 portant factors contributing to the high fertility 

 rates since the end of World War II. If so, some 

 moderate decrease in the fertility rates might be 

 expected in the next 10 to 20 years. 



On the other hand, the assumption of no further 

 decline in mortality rates after 1955-60 is not 

 entirely realistic. There are real probabilities 

 that medical science will discover far better 

 methods for the prevention and control of dis- 

 eases affecting older people. If this does occur 

 to any important extent, the effect on population 

 may offset any moderate decline in fertility. 

 Acceptance of the upper projections is not wholly 

 contingent upon maintenance of the recent high 

 fertility rates. 



Census Bureau's Projections Extended 



The Census Bureau's series of population pro- 

 jections to 1975 are here extended to 2000. For 

 each series, the Bureau's 1975 assumptions with 

 respect to age-specific fertility rates, age-specific 

 mortality rates, and net immigration are held 

 constant from 1975 onward. Using the Census' 

 method, the results of the extension are as follows: 



Projection 

 to 1975 

 (.million 



Series: persons) 



AA 228.5 



A 221.5 



B 214.6 



C 206.9 



Extension 



totooo 



(million 

 persons) 



Average 

 annual rale 

 of increase 



(percent) 



360. 



1.83 



320. 



1. 48 



275.0 



1. 00 



250. 



. 76 



