In 1924, this influx of immigrants was brought to a halt by the passing of American immigration laws which introduced the principle of national quotas and regulated the number of immigrants admitted each year by a ratio based upon previous arrivals. This penalized the Slavs severely for their immigration had been relatively recent and their quotas were reduced almost to the vanishing point. Contrariwise, the peoples of Northern Europe, who had arrived earlier, were assigned quotas which they never filled. So, from then until World War II, the American Slavic communities remained relatively static in numbers, growing only by natural increases. However, this was also a period when earlier efforts began to bear fruit and Slavic cultural and financial importance increased rapidly. The second generation, educated in American schools, was beginning to produce a new type of leadership. It took its place in the general American cultural, economic and political life with consequent results upon both the country as a whole and upon the Slavs. There was increased cooperation between the Slavs and the rest of the American population, a period of growth and development from within. After World War II, the displaced persons from Europe began to enter the United States in large numbers. From 1939 on, there came a surprisingly large number of highly educated persons, largely Poles, who were fleeing from both the Nazis and the Communists. These new arrivals revivified the intellectual and cultural interests of the older immigrants and their descendants and, furthermore, they brought the best traditions of education and scholarship from their homelands. We can thus divide the growth of Slavic influence into four periods. I. _From the beginning to 1848._ During this period, the immigrants arrived as individuals and with few exceptions were absorbed rapidly and almost completely into the main streams of American life. II. _From 1848 to 1924._ This was the period of the mass immigration, largely of unskilled laborers who came to secure the material benefits of life in the United States. Yet it was also the period when the general outlines of Slavic life in America were being sketched, organizational and church affiliations were made, and the immigrant groups were taking root as large units in the United States. III. _From 1924 to 1939._ Despite the almost complete lack of immigration, Slavic communities were beginning to attract the attention of the American public. Internally they were completing their adaptation to the American mode of life with far greater success than had seemed possible a few decades before.