The list of the most densely populated incorporated cities in the United States has some interesting features. The top four entries are all small cities (less than 1.5 mi sq; fewer than 70,000 inhabitants) located just to the west of Manhattan in Hudson County, New Jersey. Three of the top 11 – Kaser, New Square, and Kiryas Joel – are relatively new towns in the New York metropolitan area that are entirely or primarily inhabited by Hasidic Jews. All three have high fertility rates and low levels of per capita income. According to Wikipedia, “Kiryas Joel has the highest poverty rate in the nation” while New Square is “the poorest town (measured by median income) in New York, and the eighth poorest in the United States.”
One surprising revelation in the city-density list is the large number of thickly populated cities that were originally established as low-density suburbs of Los Angeles. Of the 140 U.S. cities with more than 10,000 people per square mile, 28 are in the Los Angeles region. Although still conventionally imagined as a low-density, suburban environment, the L.A. region has been densifying for decades. The sprawling city of Los Angeles itself, covering some 469 mi sq, is now moderately dense by U.S. standards. As the density map of southern Los Angeles County posted below shows, central L.A. is now heavily inhabited, with many census tracts reporting more than 30,000 people per mi sq. Quite a few outlying tracts also post high figures. Many of these areas do not appear at first glance to be densely populated, as they are dominated by low-rise buildings and include many detached, single-family houses. But the number of persons living in each dwelling unit can be high, particularly in areas with large numbers of recent migrants.
Several of small, densely populated cities in the Los Angeles metropolitan area in the northwestern quadrant of a cluster of municipalities known as the “Gateway Cities.” I have enclosed the northern portion of this “Gateway” area on maps posted above and below, excluding the relatively large city of Long Beach. The crowded little cities in this region are relatively poor and have large immigrant populations. In 2019, Business Insider placed Huntington Park in the lowest position in California on its “misery index” and in the tenth lowest nationally. The Wikipedia article on Maywood estimates that one-third of [its] residents live in the U.S. without documentation.” Maywood is also notable for being “the first municipality in California to outsource all of its city services, dismantling its police department, laying off all city employees except for the city manager, city attorney and elected officials, and contracting with outside agencies for the provision of all municipal services.”
The evolution of tiny but densely packed Cudahy, with almost 23,000 residents living in 1.18 mi sq, is particularly interesting. Cudahy was originally designed as a semi-rural garden city. Its founder and namesake, the wealthy meat-packing entrepreneur Michael Cudahy, purchased a large ranch in 1908, which he subdivided and sold off in one-acre lots. As explained in the Wikipedia article on the city:
These “Cudahy lots” were notable for their size—in most cases, 50 to 100 feet (15 to 30 m) in width and 600 to 800 feet (183 to 244 m) in depth, at least equivalent to a city block in most American towns. Such parcels, often referred to as “railroad lots,” were intended to allow the new town’s residents to keep a large vegetable garden, a grove of fruit trees (usually citrus), and a chicken coop or horse stable.
Although gardens, orchards, and farm animals are long gone, the old “Cudahy lots” may still be visible in satellite images (see the image below; I was not, however, able to find a map of the original city lots). At any rate, Cudahy gradually morphed into a crowded industrial town, giving it a legacy of environmental contamination. As noted by the Wikipedia article cited above:
On January 14, 2020, delta Airlines flight 89 dumped jet fuel Cudahy, while making an emergency landing at Los Angeles International airport. Park Avenue Elementary School suffered the brunt of this dumping. This incident sparked outrage because of the city’s previous history of environmental damage, including the construction of the same school on top of an old dump site that contained contaminated soil with toxic sludge, and pollution from the Exide battery plant.
As a final note, it is intriguing that the two main clusters of small, high-density cities in the United States are located immediately adjacent to the country’s two largest cities, New York and Los Angeles. Populous though they are, these two cities have markedly different built environments and settlement histories. New York is well known for its high population density, but Los Angeles is more commonly regarded as a low-density city anchoring an even lower-density metropolitan area. That vision is longer justifiable.