The city of Paris in France had an estimated gross domestic product of 757.6 billion Euros in 2021, the most of any European city. Paris was followed by the spanish capital, Madrid, which had a GDP of 237.5 billion Euros, and the Irish capital, Dublin at 230 billion Euros. Milan, in the prosperous north of Italy, had a GDP of 228.4 billion Euros, 65 billion euros larger than the Italian capital Rome, and was the largest non-capital city in terms of GDP in Europe. The engine of Europe Among European countries, Germany had by far the largest economy, with a gross domestic product of over 4.18 trillion Euros. The United Kingdom or France have been Europe's second largest economy since the 1980s, depending on the year, with forecasts suggesting France will overtake the UK going into the 2020s. Germany however, has been the biggest European economy for some time, with five cities (Munich, Berlin, Hamburg, Stuttgart and Frankfurt) among the 15 largest European cities by GDP. Europe's largest cities In 2023, Moscow was the largest european city, with a population of nearly 12.7 million. Paris was the largest city in western Europe, with a population of over 11 million, while London was Europe's third-largest city at 9.6 million inhabitants.

In 1938, the year before the Second World War, the United States had, by far, the largest economy in the world in terms of gross domestic product (GDP). The five Allied Great Powers that emerged victorious from the war, along with the three Axis Tripartite Pact countries that were ultimately defeated made up the eight largest independent economies in 1938.

When values are converted into 1990 international dollars, the U.S. GDP was over 800 billion dollars in 1938, which was more than double that of the second largest economy, the Soviet Union. Even the combined economies of the UK, its dominions, and colonies had a value of just over 680 billion 1990 dollars, showing that the United States had established itself as the world's leading economy during the interwar period (despite the Great Depression).

Interestingly, the British and Dutch colonies had larger combined GDPs than their respective metropoles, which was a key motivator for the Japanese invasion of these territories in East Asia during the war. Trade with neutral and non-belligerent countries also contributed greatly to the economic development of Allied and Axis powers throughout the war; for example, natural resources from Latin America were essential to the American war effort, while German manufacturing was often dependent on Swedish iron supplies.

From January 24, 2022, to February 28, 2025, the European Union (EU) institutions, such as the Commission and the EU Council, provided around 52.1 billion euros in bilateral financial, humanitarian, and military aid to Ukraine in view of the Russian invasion that started in February 2022. The highest value of allocations was recorded from the United States at over 114 billion euros. U.S. aid to Ukraine As of February 28, 2025, the value of U.S. bilateral aid allocations to Ukraine represented 0.53 percent of 2021 donor GDP. The U.S. donated the largest amount of bilateral military, financial, and humanitarian aid to Ukraine. Generally, U.S. foreign aid to Ukraine has increased since 2015. Where does military aid to Ukraine come from? The U.S., Germany, the United Kingdom (UK), and Denmark were the largest suppliers of military aid to Ukraine. In monetary terms, the U.S. bilateral military assistance to the country reached approximately 64.6 billion euros as of February 28, 2025. As part of that aid, the U.S. transported over 7,700 air defense missiles and over 1,600 air defense systems to Ukraine and other European partners as of January 2025. Furthermore, the U.S. delivered the most units of M777 howitzer artillery to the country.