Thanks for correcting me on the information source, DT. Both state and federal population estimates will vary, until we know for sure the exact populations, like the US census held every 10 years. City and county governments need to upkeep on projected populations to better serve their jurisdictions to upgrade public services for the common good.
The reason why Los Angeles annexed a great deal of land (i.e. the formerly incorporated communities of Hollywood, Watts, Venice and San Pedro) and the then-rural agrarian San Fernando Valley which was mostly urbanized by the late 1940's has much to do with acquisition of rights of water supply services, especially after the completion of the Los Angeles Aqueduct. In San Pedro's case has more to do with the opening of the Port of Los Angeles adjacent to the port of Long Beach. The city of L.A. is over 500 (504?) square miles (470 land, 34 water) and home to 3.8-3.9 million inhabitants.
Two other US cities: Oklahoma City, OK (it's city limits extends to rural expense of land to 621 square miles) and a greater municipal claim of undeveloped land is Juneau, Alaska at 3,255 square miles! larger than the tiny states of Delaware and Rhode Island combined. Both cities are state capitals, yet Juneau also an Alaskan borough with a total population of 32,000 is only less than one percent developed.