Why are unions not as prevalent in western states?

The European Union (EU) is a political and economic partnership that represents a unique form of cooperation among sovereign countries. The Union is the latest stage in a process of integration begun after World War II, initially by six Western European countries, to foster interdependence and make another war in Europe unthinkable. Today, the EU is composed of 28 member states, including most of the countries of Central and Eastern Europe, and has helped to promote peace, stability, and economic prosperity throughout the European continent.