Canadian Jewish identity underwent a profound transformation between 1900-1960, shifting from ethnic-based community solidarity toward religious-institutional affiliation more characteristic of American Judaism. As Canadian Jewish population surged from 15,000 to 280,000, concentrated in Montreal and Toronto, traditional European patterns of Jewish communal organization gave way to congregation-centered religious expression. Comparative analysis of American and Canadian Jewish communities, combined with census data analysis and historical documentation, reveals accelerating "Americanization" of Canadian Jewish religious structure and identity formation. Census responses show a widening gap between religious and ethnic self-identification - from just 1.5% differentiation in 1941 to 32% by 1961. Synagogue development statistics demonstrate corresponding institutional changes, particularly in non-Orthodox congregations which expanded significantly after 1935, reflecting generational adaptation to North American patterns. Through examination of demographic patterns, congregational growth, and evolving self-identification, the research documents Canadian Jewry's adaptation to North American religious pluralism while maintaining distinctive cultural elements within Canada's multicultural framework. Geographic proximity and cultural influence from American Judaism emerge as fundamental forces shaping Canadian Jewish institutional development and identity formation across this pivotal period.