The ZIP code 90403 in Santa Monica, California, with an area of 1.39 square miles, exhibits a dense urban lifestyle based on its population density, which has consistently remained above 16,000 people per square mile over the past decade. In 2022, the population density was 16,935.25 people per square mile, indicating a highly urbanized environment with multi-story residential buildings, commercial establishments, and well-developed infrastructure.

The historical population data from 2010 to 2022 shows that the area has maintained a relatively stable population, fluctuating between 23,295 and 24,374 residents. This stability suggests that the area is well-established and has likely reached a mature stage of urban development, with limited room for further growth or significant changes in population density.

Given the 2022 population of 23,540 and the national average household size of 2.61, the estimated number of housing units in the ZIP code is approximately 9,019. This figure, along with the high population density, indicates a predominance of multi-unit residential structures, such as apartments and condominiums, which are typical of dense urban areas.