What contributed to the convergence of the development paths of the countries of Western Europe

What contributed to the convergence of the development paths of the countries of Western Europe and North America in the second half of the 20th century?

After the coalition forces won a victory over Germany, the world fell into two opposing camps. One camp was led by the USSR, it was socialist, and the second camp was led by the United States, it was the capitalist west. After that, the Cold War and the arms race began. In the countries of Western Europe and North America there was just a capitalist system, and therefore these countries were very close and cooperated closely with each other in opposition to the USSR and the imposition of communism on other countries.