The first recognition of Europe Day was by the Council of Europe, introduced in 1964. The European Union later started to celebrate its own European Day in commemoration of the 1950 Schuman Declaration, leading it to be referred to by some as "Schuman Day" or "Day of the united Europe". Both days are celebrated by displaying the Flag of Europe.

The "Europe Day" of the EU was introduced in 1985 by the European Communities (the predecessor organisation of the EU) The date of commemorates the Schuman Declaration of 9 May 1950. The declaration proposed the pooling of French and Western German coal and steel industries, leading to the creation of the European Coal and Steel Community, the first European Community, established in 1952.

Following the foundation of the EU in 1993, observance of Europe Day by national and regional authorities increased significantly.  Germany in particular has gone beyond celebrating just the day, since 1995 extending the observance to an entire "Europe Week" centered on 9 May.

In Poland, the Schuman Parade, a Polish organisation advocating European integration established in 1991, first organised its Warsaw Schuman Parade on Europe Day 1999, at the time advocating the accession of Poland to the EU.

Observance of 9 May as "Europe Day" was reported "across Europe" as of 2008. In 2019, 9 May became an official public holiday in Luxembourg each year, to mark Europe Day.

According to en.wikipedia