June 25, 1948
In 1948, Congress carried out the first major overhaul of the Judicial Code since it was originally compiled in 1911. The 1948 code made a few substantive changes in the law, some of which expanded federal court jurisdiction. For example, provisions regarding diversity jurisdiction were altered to include citizens of U.S. territories and the District of Columbia in addition to citizens of the states.
View the timeline: The Jurisdiction of the Federal Courts