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BELL SYSTEM TECHNICAL JOURNAL 



The improvement of service has been associated with a particularly- 

 rapid growth of very long haul telephone business and a consequent 

 increase in the average length of telephone circuits used for interurban 

 and long distance work. This is illustrated by Fig. 3 which shows the 



160 



120 



O 100 



o 



a. 80 



ui 



2 



60 



40 



20 



1920 1922 1924 1926 1928 1930 1932 1934 



YEAR 



Fig. 3 — Long haul telephone circuit growth of typical circuit groups. 



growth in the last few years and the expected growth for the next few 

 years of typical circuit groups of different lengths. In the period 1925 

 to 1929 while telephone toll business as a whole increased 59 per cent 

 New York-Chicago business increased 170 per cent and the combined 

 Chicago and New York business to Los Angeles and San Francisco 

 380 per cent. From the standpoint of coordination with other electric 

 circuits the very long telephone circuit offers a more dif^cult problem 

 than the circuit of moderate length because of the cumulative eflect of 

 exposures in different sections. 



