The cover above was sent at the international UPU rate of 5 cents for first class mail traveling outside of the continental United States. It was canceled on board Train Nr. 701 on the Boston, Providence and NY Railroad. 

RPOs or Railway Post Offices were operated on special mail cars. The mail was actually sorted and canceled on board the train between destinations.  

SEE: 1887 Boston, Providence & NY Cover for further information and background history on the this railroad.

The eastern border of Alsace sits on the Rhine River and it has been at the heart of German and French hostilities since it was first created. On the death of Charlemagne, his grandsons divided his Kingdom into three parts. Alsace or Lotharingia, as it was then known was given to Lothar. At various times during its history Alsace have been claimed by both Germany and France. After the Franco-Prussian War (1870) and until the end of World War I, it was part of the German Empire. After World War I and again after World War II, Alsace became a part of France. In 1892 when the above letter was sent, it was under German rule.

A settlement has existed on the present day site of Strasbourg since the "Bronze Age." During the Roman Empire it was called Argentoratum and was one of the main defensive outposts against the Germanic tribes. Due to it's location and a major bridge across the Rhine River, Strasbourg became a major trade route during the European Feudal and Reformation periods. During the 15th century Strasbourg became a free republic, but in 1697 it was annexed by France. Strasbourg is the seat of the  European Parliament and the European Court of Human Rights.