The ongoing effects vary from country to country depending on how that location has evolved in the post colonial era with the expansion of Capitalism as the main economic system for the exploitation and distribution of the planetary resources for the use of our own species. That diversion of resources has come at the expense of the majority of habitat available for species living in the wild, resulting in the ongoing extinction of thousands each year both on land and in the oceans. That has destabilized the planetary ecosystem, endangering the fertilization strategies of plants and opening the door for massive monoculture crop failures. While for now depopulation of homo sapiens is occuring relatively slowly from the birthing side, this eventually will be overtaken on the death side of the equation by increasing mortality due to famine and disease.
South Korea has become the Poster Child country for fertility rate decline, most recently coming in at a 0.7 TFR and is likely to suffer extreme social problems in the near future because of it, but for our purposes the FsoA provides a more comprehensive view of the situation as it is playing out inside the industrial economy. Because of its position as the preeminent destination target for most of the world's population of immigrants and refugees, most of the demographic and economic problems stemming from global depopulation will likely remain masked for a while. That however depends heavily on the acceptance and integration of those immigrants into the Amerikan economy, which is not at all clear in the current political playing field. Republicans are savagely anti-immigration particularly among the Trump supporters, and only very moderate members of that party concerned with how they will find low wage workers for bizness have anything resembling a sane approach. Democrats are more realistic about the need for immigration in general, but do face some resistance from labor groups seeking to drive up the value of workers. Ongoing wars and the threat of terrorism from immigrants fleeing countries which are anti-Amerikan or Muslim creates a political problem that layers on top of the economic one, further complicating the issue.
Despite the current political resistance to immigration, it has been the primary driver for economic growth since the Europeans first arrived and started systematically eliminating the original occupants, who themselves had immigrated here a few thousand years earlier from Asia via land bridge across the Bering straight during the ice age. The iconic landmark of thee Statue of Liberty in NY harbor stands there to welcome refugees looking for a better life, which many found through successive waves from different places at different times.
While the continent was mostly empty of white people through the early 1800s, absorption of new immigrants was relatively easy, the frontier simply kept being pushed further westward as the cavalry cleared the land of the native populaation. The Indian Wars only came to a close at the end of the 19th century, and when WWII ended in 1945 the population was still largely rural. From 1940 to 1980 though, the distribution changed radically, and farmers dropped from 30% of the population to 3%. During the same period the Suburban Model of housing was developed in conjunction with the automobile and the interstate highway system. Inward immigration from other countries continued, but internally andd simultaneously the population began to redistribute. It is this redistribution which has led to the decrease in Total Fertility Rate (TFR) since the mid 20th century.
As the primary ingress point for new immigrants, the simplified model below shows how the new population is absorbed and then redistributed to the surrounding suburbs and then outward to other cities and suburbs across the country.
Graphic1: NYC Steady StatePopulation Schematic
The densely populated core 5 boroughs of NYC has maintained a relatively steady 8M people since the mid 20th century. It is basically maxed out in population size with urban density. Individuals and small families arrive here and try to find increasingly less available affordable housing, but as soon as they are able to economically leave the city for the suburbs or other places if they want to raise children. The NYC Public Schools are failing, and the costs of raising children inside the city are astronomical. Opportunities for activities like club teams, gymnastics and outdoor sports either don't exist or are incredibly expensive.
Suburbs around the city have become increasingly unaffordable, and for some of the closer ones density has been increased to include attached houses and multistory condominiums, which while they may feature as many bedrooms as a typical McMansion, they don't have the backyard and garage space of the typical suburban home. It's not a housing strategy that encourages family growth.
Finding NYC and its suburbs to be out of range economically for young couples interested in raising a family, the 21st century began with new immigrants leaving NY to head for newer growing cities around the country where they could afford to get into a McMansion and begin to live the American Dream. Houses were sold with LIAR and NINJA loans, leading eventually to the 2008 Financial Crisis and collapse of the real estate market. The 15 years since has seen a variety of financial bailouts and gimmicks to keep the economy afloat, as well as the COVID pandemic and its associated lockdowns and economic consequences. None of this has been particularly helpful toward improving the TFR and making raising children any more possible or desireable.
Graphics 2 & 3 here are a simplified schematic of the evolution of the Amerikan housing market beginning at the close of WWII at the beginning when 30% of the population was involved in farming and the first Suburban subdivisions were being carved out of farmland close to the cities. I even remember one small dairy farm not far from my attached house in Queens in the early 1960s.
Graphic2: USA Population Schematic 1945
During this period, new arrivals would take up residence in apartment buildings that were being vacated by prior tenants as they gained economic success and moved out to the surrounding suburbs. This left apartments available for each new wave that arrived, while the population of NYC itself remained more or less constant.
Over time, this has filled up all of the available land within a 1 hour commuting distance with suburbs, and little new housing gets built except to raze some of the oldest houses and update with newer, more expensive models. The Greater NY area as a result also is fairly constant at around 20M people. People coming into NY as new immigrants can't find apartments, because people in those apartments can't find houses they can afford to move to. New immigrants as a result often in many cases have to leave the NYC area right after being processed by immigration...NYC will even give them free bus tickets anywhere they want to go. Graphic 3 shows a schematic of the FsoA as it is in 2023.
USA Population Schematic 2000
The same situation is true in all the main ingress cities where immigrants land or cross the border first, Seattle, San Francisco, Los Angeles, Phoenix, Houston, Miami all have the same problems housing immigrants and finding affordable housing in saturated suburban communities. People stuck in the cities delay starting families until they can get into a house, which becomes less possible every year with each new immigrant family.
The question is, can these trends be reversed through goobermint policy actions? It does not appear that financial incentives are working in any of the places they are being tried, but this may simply be because the incentives aren't big enough. A $10K bonus from da gobermint for popping a bun out of the oven gets spent before the kid is even a year old, even with expanded maternity leave. Given the labor force shortage that currently exists also, who replaces the new mothers that take the extended maternity leave?
Since it is evident that farmers have more babies, encouraging more people to go back to farming as a way of life seems like the only real solution to the fertility rate problem, but the economics of the family farm are what caused the migration to the cities in the first place. Increasing subsidies to small farmers while decreasing them to agribiz conglomerates sounds like a good idea on paper, but getting such changes through Congress is probably an impossible task. It's also unclear how you would take the big industrial farms and break them up again into smaller family farms after it took decades to consolidate all of them.
Long term, the prognosis doesn't look good for industrialized nations for maintaining or growing their population size solely through internal reproduction as long as the urban model of living is perpetuated. Global TFR remains positive at 2.3, however the non-industrialized countries of the 3rd world with high TFR also generally have high mortality rates so not all of these countries can be counted on as a source of new immigrant supply. These countries also reflect a much smaller percentage of the total world population than countries with a TFR below 2.1, since all the largest nations now, India, China, USA, Japan fall below replacement levels. As a result, continuing current trends, global population size for homo sap will likely begin to fall shortly after mid-century.
This does not mean we will breed ourselves out of existence anytime too soon. It does however mean that economic models that depend on perpetual growth to function will inevitably fail moving forward in the timeline. Most important of those are retirement models like Social Security which depend on a growing source of new workers to remain economically solvent. That crisis will confront the FsoA long before the total population begins to fall. Insolvency for SS is less than a decade away with the current funding model. That is the proximal problem of our dropping fertility rate da goobermint will face in the 2030s, or sooner if the exponentially increasing total debt is not brought under control.