62 



1851 First government act establishing waterfront limits and regulat- 

 ing construction of wharves. (Wharves could be built only 

 beyond waterfront line on extensions of city streets and for a 

 distance not to exceed 200 yards. This caused the majority 

 of original wharves built beyond this line to be 80 by 600 

 feet, which remained standard until about 1909.) 



1867 First seawall started, cutting off area of many original wharves. 



1869 Completion of transcontinental railroad Introduced competition 



with shipping interests. 



1878 New waterfront line established by action superseding act of 



1851. 



1878-1890 Final seawall built along north section of waterfront cutting off 



original wharves and causing abandonment of first seawall. 

 Old pier abandoned and new piers built to conform with 

 new line. 



1904-1922 Seawall built along south section of waterfront cutting off 



original wharves. Old piers abandoned and new piers built 

 to conform. 



1909 Size of new piers increased to 130-140 by 650-700 feet; slips 



200-220 feet wide. 



1910 Development of vehicular traffic, rapidly increasing, required 



special ferry service, particularly for automobiles. 



1912 Size of new piers increased to 200 by 800 feet; slips 250 feet wide. 



1914 J Panama Canal completed, introducing increased shipping com- 

 petition with railroads. 



1919 Size of new piers increased to 235 by 1000 feet; slips 300 feet 



wide. 



1923 Construction of transbay vehicular bridges started. 



The following tabulation gives the approximate economic life of various San 

 Francisco wharves, as represented by the actual life, from the time when they were 

 first operated until operation stopped and they were removed, the limitation of life 

 having been occasioned by some of the conditions cited above. It should be borne in 

 mind, as emphasized in the preceding discussion, that the actual life of a structure in 

 most cases does not coincide with the true economic life, due to influence of the (poten- 

 tial) physical life. Short lived construction materials may, of course, make the actual 

 life shorter than the potential economic life; but in such cases structures are usually 

 renewed by repair or rebuilding. As a usual thing the actual life is carried beyond the 

 true economic life by a residual physical life, when the two do not coincide. In respect 

 to most of the structures listed below, however, such exaggeration of the economic life 

 is not belie\'ed to be serious, since during that period and in the structures listed the 

 use of construction capable of a physical life greatly in excess of current economic life 

 was extremely limited. It will also be understood that the life indicated is not neces- 

 sarily that of the original construction, the majority of the structures having been 

 renewed or rebuilt to a \'arying extent during their total life. 



