The ZIP code 90404 in Santa Monica, California, has experienced steady population growth over the past decade, with the population increasing from 21,176 in 2010 to 24,465 in 2022. The population density has also risen accordingly, from 10,483.17 people per square mile in 2010 to 12,111.39 people per square mile in 2022. Given the ZIP code's area of 2.02 square miles, the estimated number of housing units corresponding to the 2022 population is 9,373, assuming the national average household size of 2.61 persons per household.

Based on the population density data, ZIP code 90404 can be classified as a dense urban area. Dense urban areas are characterized by high population densities, typically ranging from 10,000 to 30,000 people per square mile. These areas often feature multi-story residential buildings, commercial buildings, and advanced infrastructure. The lifestyle in dense urban areas is highly urbanized, with a focus on vertical living and premium amenities. Residents in these areas prioritize proximity to major business districts and minimal commute times.

The consistent population growth and increasing population density in ZIP code 90404 suggest ongoing urban development and a growing demand for housing and services. As the area becomes more densely populated, it is likely to experience further development of high-rise buildings, commercial districts, and advanced infrastructure to accommodate the growing population.