Immigrants often stayed in neighborhoods with other people from the same country. what were these neighborhoods called apex

Ethnic Enclaves is the correct asnwer.

Throughout history, we see immigrants moving from one place to the other and  often staying in neighborhoods with people with whom they shared the same nationality, culture and similar habits. In Sociology and Anthropology, an ethnic enclave is defined as a geographic area where a community that shares similar background maintains a strong sense of identity and customs from their place of origin. These ethnic enclaves were the most common option for these immigrants since they felt  more welcome and safer from prejudice and discrimination.