I thought the San Fernando Valley was a major drag on L.A.'s density, but that's not really the case. Backing out the Valley from L.A. appears to only slightly move the needle up in terms of density.
- San Fernando Valley population (including L.A.): 1,826,028
- Valley minus Burbank, Calabasas, Glendale, Hidden Hills, and San Fernando: 1,473,236 in an area of 194 sq. miles for a density of 7,577 ppsm.
- Los Angeles minus Valley population: 2,425,511 in an area of 275 sq. miles for a density of 8,802
So removing the Valley just slightly increases L.A.'s 2020 density from 8,312 ppsm to 8,802 ppsm.
Prewar L.A. also did not really match the big eastern cities in terms of scale of density. Los Angeles's 1950 population was 1.9 million and roughly 200k-300k of the population was in the San Fernando Valley by then. Los Angeles would have still easily been in the top 5 by population without the Valley, but its population density would've
still been far lower than the rest of the top 5 in 1950:
U.S. cities with greater than 1 million in 1950 by population density (in people per square mile)- New York - 26,306.52
- Chicago - 15,951.37
- Philadelphia - 15,459.74
- Detroit - 13,402.67
- Los Angeles - 4,201.18 (w/o Valley between 6,074 ppsm and 6,437 ppsm)