Harlem represented an escape from the Jewish ghetto, it meant that assimilating to American ways was such a priority that it shook up Jewish leadership. Assimilation evoked new programs to keep Jewish people affiliated with the Jewish community. Such dynamic rabbis as Bernard Drachman, Herbert Goldstein and Mordechai Kaplan all ordained by the Jewish Theological Seminary of the America, instituted new outreach programs that attempted to synthesize Jewish traditions and American culture.
This was an era when the Jewish Theological Seminary produced so called "orthodox" rabbis. The Seminary's mandate was to produce American rabbis who could inspire Jewish youth to observe Judaism without sacrificing one's American identity. Clearly, Mordechai Kaplan, later the founder of Reconstructionist Judaism veered off to found a new strand, however in the beginning he served Orthodox congregations in Harlem.
Of the three, Herbert Goldstein was truly Orthodox having received a traditional ordination from a sage in the Lower East side before entering the Jewish Theological Seminary. He founded the (Orthodox) Institutional Synagogue which is now situated on the West Side with extensive programing reaching out to young Jewish people.
Ultimately, by the 1930's, the Jewish settlement of Harlem emptied to other emerging neighborhoods in Brooklyn and the Bronx because of its overcrowding and its own Jewish 'ghettoization'. The pestering problem of assimilation, the demand to Americanize could well define the American Jewish community throughout its history.