America's long-term growth rate is generally higher than that of Western Europe. Throughout every 2-decade period in American history until the 1980s, GDP tended to increase by around 3% a year on average, compared to somewhere between 1 and 2% for Western Europe.

In 1945, the United States surpassed Western Europe for the first time, but only because of the temporary disruption of World War 2. in the decades following, some Western European countries saw high single digit growth rates year over year as they recovered from the war. The US in the late 1940s also provided a sum of aid between 1948 and 1952 equal to 3% of Western Europe's GDP, representing a large financial redistribution from the US to Europe.

In this period European countries also embarked on institutional innovations that shifted their long-term growth rates. This was most pronounced in Germany, whose financial and economic reforms are famous. Less well known were restructuring efforts in France and especially Italy which resulted in 30 years of growth averaging more than 5% a year. Western European countries also tightened trade links with one another. Temporarily, this led to an economic boom, but over time, the United States was able to catch up again due to its structural advantages.

These advantages are debated by economic historians, but almost all who have written about the issue agree that America's vast natural resources, obsessively pro-business governments, its abundance (and therefore relative cheapness) of land, and its status as a magnet for high-skilled immigrants give it huge advantages over Europe. The last factor is self-promoting - immigrants that came to the United States after World War 2 in general possessed far greater levels of education and wealth in their countries of origin than those who migrated to Europe. This both because of the US's comparatively generous immigration policy, and because wages in the US were already higher due to the country's other advantages. The contributions of these immigrants to growth ensured wages would remain higher, thereby ensuring that the United States would remain the prime destination for high-skilled immigrants in the future.

That is not to say that Western Europe could not have overcome the US's natural advantages and reasserted its historical prominence in the world economy. Some countries, most famously Japan and Singapore, consistently outgrew the US during the Cold War, even after they had become developed countries. However, their governments were far more aggressive and single-minded about growth policy than those in Western Europe ever were. While France, Germany, and Italy did devise robust growth strategies during the Cold War, they did not even remotely approach the complexity of the approaches of the handful of developed countries that did outperform the US in the late 20th century. And, with Singapore's exception, even those countries eventually fell behind the US as well. Japan's GDP per capita at one point exceeded that of the United States, but by the turn of the 21st century, the US had caught up.

What Americans consider to be their country's "normal" growth rate is fast in most other developed countries. A wealth of resources, relatively cheap rural land, and decent political institutions for growth enable a high wage economy. High wages attract high-skilled immigrants, which increases economic growth in a "virtuous cycle", but one which ensures that other countries cannot compete when it comes to attracting foreign talent. This phenomenon is not well known simply because it works so slowly. Throughout the 1970s, 80s, and 90s, the US exceeded the growth rates of most Western European countries by anywhere between 1 and 2%. However, over the course of 3 decades, this greatly changed the economic balance of the Atlantic.

Sources:

Cohen, Elie & Pisani-Ferry, Jean. Economic Institutions and Policies in the US and the EU: Convergence or Divergence?

Feldstein, Martin. Why is Growth better in the United States than in other Industrial Countries?

Broadberry, Stephen. Economic Growth in Europe and the United States Since 1870: A Quantitative Economic Analysis Incorporating Institutional Factors.