The 1857 French Treaty

The 1857 Postal Treaty Between U.S. and France, Routes and Rates

The 1857 postal convention between the United States and France became effective on April 1, 1857 and was in effect until December 31, 1869. The treaty called for a postage rate of 15¢ (8 decimes) for each letter weighing up to one-quarter ounce sent from locations in the United States to all destinations in France. Multiple rates were in a simple progression. Unpaid, or insufficiently prepaid which was treated as unpaid, letters to France were charged 8 decimes per 7.5 grams. The treaty called for all credits to France on prepaid mail to be shown in red and all debits in black. 

There were four schemes for division of the 15¢ postal rate that varied with the mode of conveyance used. France was required to pay Great Britain for all charges on mail carried by British packets and on all transit mail. The table below shows the credits and debits on the 15¢ rate. Havre was designated as an exchange office as was the ambulant (railway post office) between Calais and Paris. Most mails sent via Great Britain were transmitted in closed bags to Calais and sorted on the ambulant between Calais and Paris except those addressed to Havre which were sent, via Southampton, to Havre. Paris was made an exchange office on April 1, 1861 and most mails were postmarked upon arrival, again excepting those addressed to Havre.

British Packet - The British owned lines operated steamers from New York, Boston and Portland on a regular schedule. Mails were transported in closed bags across Great Britain to France at the expense of France. (Routes 1 to 4)

American Packet via Britain - Several steamship lines carried French mails from New York to Great Britain under contract to the United States. The American mails were off-loaded in Great Britain and carried onward to France by the British at French expense. (Routes 5 to 8)

American Packet Direct - A few steamship companies operated under contract from the United States to carry mail directly to France. British transit charges which had to be paid by France applied to the previous categories but mail carried directly to France by American or French packets were not subject to these charges. (Routes 9 to 11)

French Packet - In June 1864 the Compagnie Generale Transatlantique, or French Line, began operating between New York and France. The company was subsidized by the French government. (Routes 12 and 13)

A PDF file of route maps and markings is here.