Residential segregation has been an issue in the Bronx, just like everywhere else in the United States, ever since the borough became urbanized. During the building booms of the twenties, some buildings like the Lewis Morris were restricted and did not rent apartments to Jews or Catholics. African-Americans and Hispanics only lived in certain neighborhoods and there would be desegregation battles over churches, public housing, beaches and even a White Castle, some of which I will write about in February for African-American History Month.
Back in the twenties, the largest group moving to the Bronx were Ashkenazi Jews with roots in Eastern Europe or if they were Sephardic, the Balkans. Many Jews were active in real estate, construction and architecture.
An interesting example of this time period are the Allenby and Beaconsfield Apartments on Sheridan Avenue, constructed in 1929. They are typical apartments of this period, but note who the buildings are named for. Edmund Allenby (1861-1936), was a British officer, respected in Jewish community for leading the British force that conquered Jerusalem from the Ottoman Empire, an act that was imbued with religious and political meaning to Jews worldwide, especially as it led to the British Mandate of Palestine.
The Beaconsfield is named for British prime minister Benjamin Disraeli (1804-1881), known as Lord Beaconsfield. In a way the names are coded in that they are typical English-style apartment names to passers-by but would have extra significance to Jews, as they did for me when I passed them ninety years after they were built.