Czech Republic–Slovakia relations
Before 1918, both countries were part of Austria–Hungary. However, after the Ausgleich of 1867 Czechia belonged to the Austrian Empire while Slovakia belonged to the administratively separate Kingdom of Hungary, and between 1918 and December 31, 1992, both countries were part of Czechoslovakia. 
Both countries established diplomatic relations on January 1, 1993. These international relations are usually referred to or described as "very good", "cordial", and "above standard" in the media. When a Czech or Slovak president is inaugurated, very often his first international visit is to the former part of the common country. The same custom applies to newly elected prime ministers of the Czech Republic and Slovakia.
Slovak Americans
In 1915, the leaders of the Czech National Alliance and the Slovak League of America signed the Cleveland Agreement, in which they pledged to cooperate for the common goal of independent statehood for the Czechs and Slovaks. The agreement's five articles laid out the basics of a future joint state for the two nationalities. Three years later, the Pittsburgh Agreement was concluded by representatives of Czechs and Slovaks at a meeting of the American branch of the Czechoslovak National Council in Pittsburgh. The agreement endorsed a program for the struggle for a common state of Czecho-Slovakia and agreed that the new state would be a democratic republic in which Slovakia would have its own administration, legislature, and courts. On October 18, 1918, the primary author of the agreement, T. G. Masaryk, whose father was Slovak and mother Moravian, declared the independence of Czechoslovakia on the steps of Independence Hall in Philadelphia, Pennsylvania. He was elected the first President of an independent Czechoslovakia in 1920.