The world experienced substantial changes in the late 19th century which created an environment favorable to an increase in and development of international financial centers. Principal among such changes were unprecedented growth in capital flows and the resulting rapid financial center integration, as well as faster communication. Before 1870, London and Paris existed as the world's only prominent financial centers. Soon after, Berlin and New York grew to become major centres providing financial services for their national economies. An array of smaller international financial centers became important as they found market niches, such as Amsterdam, Brussels, Zurich, and Geneva. London remained the leading international financial center in the four decades leading up to World War I.