DOCUMENTARY HISTORY OF THE FLORIDA CANAL 39

 11. Comparison.-The potential cargo tonnage of the canal for 1929 %y care-
ful analysis amounts to 62 percent of the ocean-borne tonnage of all the Gulf
ports. The rapidly increasing need for a ship canal is indicated by the fact that
for the year 1929 the potential canal tonnage was much greater than the total of
all cargoes received and shipped from all Gulf ports for the year 1920 (but 9
years earlier) and was nearly two and one-half times the tonnage of all cargoes
in-bound and out-bound at all Gulf ports in the year 1910.
 The total cargo tonnage of the Gulf ports is 23 percent of the total foreign and
domestic cargo tonnage of all United States ports. Twenty-five percent of all
cargoes exchanged with foreign countries and 35 percent of the export cargo
tonnage of the whole United States is credited to the Gulf ports. Using the figures
for the year 1929 the potential cargo tonnage of the Florida Cross State Ship
Canal was 250 percent of the average annual cargo tonnage transiting the
Panama Canal for the 15 or 16 years of its use.
 12. Vesel movement.-While it is the cargo "that pays the freight" the in-
vestment value of the waterway cannot be determined directly from the cargo
tonnage. This is carried in vessels of many types and sizes, operating with vary-
ing load factors ranging from simple water ballast in-bound to a superload con-
dition of valuable commodities out-bound. It is therefore necessary to study
the ships in the Gulf trade. This was done in utmost detail. The results are
set out in the numerous tables in our economic study, but some of the principal
facts may be stated, as follows:
 In 1929 not less than 1,487 separate vessels made one or more direct voyages
between ports of the Gulf and ports of the Atlantic north of the thirtieth parallel.
These vessels made 10,341 voyages with a total of 90,134,435 dead-weight tons
capacity. All this was potential canal traffic-it would have profited by the
existence of a suitable ship canal across the State.
 This traffic was 16 percent of the number of all entrances and clearances at
 all United States ports, and it was 30 percent of the total tonnage of entrances
 and clearances in our entire foreign trade.
 13. Comparative data.-The net tonnage of the 10,341 voyages exceeds the
 total net tonnage of all American and foreign vessels entered at all American
 seaports from foreign countries during any 1 year prior to 1921, except 1914,
 and there the difference was very slight.
 This same potential net tonnage exceeds the combined net tonnage of all en-
 trances and clearances to or from all foreign countries, of all vessels, both foreign
 and American, steam and sail, at all United States seaports for any year prior
 to 1897. In other words, the potential canal traffic, according to the figures of
 1929, is greater than the total ocean-borne commerce for the entire United States
 for the year immediately preceding the Spanish-American War-only 35 years
 distant.
 This same potential net tonnage exceeds the total net tonnage of all com-
 mercial vessels transiting the Panama Canal for the first 6 years of the use of that
 important project.
 14. Traffic statistics.-The most painstaking and exhaustive research has re-
 suited in the following determination as to potential traffic for the proposed
 north Florida ship canal for the calendar year 1929 had the project b-en com-
 pleted and in operation at that time:
 Transits-------------------------------------- --------- 10,341
 Dead-weight tons ---------- ----.----------------------- 90, 134. 435
 Gross tons---------------------------------------------- 61, 473, 998
 Net tons..------------.. .. -- --..--- -----. ----------- 38, 545, 124
 Cargo tons of 2,000 pounds- ...---------------_---------. 45, 174, 704
 Cargo value--------------------------------------- $1, 619, 388, 906
 Immediately following are two tables presenting the principal divisions of
 these items.