In New York he set himself the task of uniting the Jewish communities. In 1880 the city contained around 50,000 Jews mostly of German origin. By 1900 there were nearly a million Jews, most coming from what is now Poland, Hungary, Romania, Belarus and Ukraine, making it the largest Jewish population in the world. On 11 October 1908 he was chairman of a conference of Jewish organisations. The invitations to which, in English and Yiddish, had also been signed by labour leader Joseph Barondess and Judge Otto A. Rosalsky, amongst others. The conference authorised the formation of a representative community, the Kehillah, and gave Magnes the power to appoint an executive committee. The 25 man committee included Professor Solomon Schechter and Joseph Silverman. They called a convention in February 1909 to form a constituent assembly. Two hundred and twenty-two organisations responded, including 74 synagogues and 42 mutual benefit societies, out of some 3,500 Jewish organisations existing in the city at the time. The Kehillah's aim was to be: