The present Hungarian-Slovak international boundary stems from the treaties and acts ending World Wars I
and II. No treaty prior to 1918 is of significance for the boundary alignment since the region was controlled
by the Austro-Hungarian empire and was previously part of the Hungarian Kingdom.
The Treaty of Peace between the Allied and Associated Powers and Hungary and Protocol and Declaration
signed at Trianon on 4 June 1920 included a detailed delimitation of the boundary (Article 27, paragraph 4).
Article 29 of the treaty created a boundary commission to demarcate the boundary on land. Where the
boundary followed a waterway, according to Article 30 of the treaty, the boundary should follow the
median line in non-navigable waterways and the thalweg in navigable waterways.
A Czechoslovak-Hungarian Boundary Commission worked from 1921 to 1925 on the demarcation of the
boundary. Maps of the boundary were incorporated into the Convention relating to the Settlement of
Questions arising out of the Delimitation of the Frontier between the Kingdom of Hungary and the
Czechoslovak Republic signed at Prague on 14 November 1928 with ratifications exchanged at Budapest on
2 December 1930. The 1928 Convention provides detailed descriptions of the management of the
boundary.
Though the boundary was altered temporarily by the Vienna Award of 2 November 1938, this was annulled
by the Treaty of Peace signed on 10 February 1947 by Hungary and the Allied powers which came into
effect on 15 September 1947. The boundary had been reduced in length however by the transfer of
5,500 square miles of Ruthenia from Czechoslovakia to the Soviet Union by the Moscow Agreement signed
on 29 June 1945 by Czechoslovakia and the Soviet Union. This shortened the Hungarian-Czechoslovak
boundary by about 50 miles, though it did not alter the alignment of the boundary line - now between
Hungary and Ukraine