Hardly a week goes by that you don’t read or hear about affordable housing challenges afflicting American cities in general and the District in particular. What are the causes of this persistent, seemingly intractable problem?

Three interrelated, real-world forces have led to decreasing availability of housing for moderate- and low-income households: rising costs of land and construction; increasing costs of owning or renting a place to live; and diminishing sources of financial subsidies for creating below-market rate dwellings. In high-cost Washington, gainfully employed, above-minimum-wage public and private-sector workers would be in the moderate-income category, while minimum-wage, hourly workers would be in the low-income category.

These real-world forces seem to be unacknowledged in a lawsuit against the District, filed in April in U. S. District Court by lawyer Aristotle Theresa. According to Washington Post reporter Paul Schwartzman’s article last month, rather than directly addressing housing affordability issues, Theresa’s lawsuit alleges that D.C. planning agencies and government officials instead intentionally conspired to produce “widespread gentrification and displacement.”

The lawsuit claims D.C. policies are “classist, racist and ageist,” intended to serve the “creative class” — mostly young, white, relatively affluent professionals — rather than needy, longtime D.C residents.

Theresa wrote that such policies were “calculated to re-segregate black communities into white upper-class and creative-class communities,” Schwartzman reported, and “to welcome preferred residents and displace residents inimical to the creative economy.”

The D.C government allegedly “discriminated against poor and working-class African Americans,” disregarding their concerns.

But by blaming local government officials, policies and programs, and impugning their motives, the lawsuit offers an incomplete picture and explanation of market conditions and forces that lead to neighborhood gentrification and displacement, conditions and forces over which D.C. government officials have little control.

The crux of housing affordability problems is a lack of money for necessary subsidies, not a lack of worthy aspirations. Despite the best efforts of D.C. mayors and council members, housing-assistance funds have never come close to matching affordable-housing needs and demand.

Until the 1980s, federal and state subsidy funding for housing priced below market was relatively more available. Indeed, after World War II, helping low- and moderate-income Americans gain access to decent housing was a national policy goal. This was codified in the 1960s with the creation of the U.S. Department of Housing and Urban Development and “Great Society” federal legislation.

Numerous federal housing programs provided direct funding subsidies, low-interest loans, low-cost mortgage insurance and loan guarantees. Funding assistance was available to local public housing authorities, nonprofit housing sponsors, private real estate developers, home buyers and tenants.

During the 1970s, my architectural firm designed a number of low- and moderate-income housing projects, some federally subsidized. Several were built exclusively to serve elderly tenants. But America changed markedly after the 1970s.

In the 1980s, President Ronald Reagan wanted to shut down HUD. That didn’t happen, but he and Congress did succeed in eliminating or curtailing federal housing subsidy and finance programs. Housing and urban development ceased being a national priority as HUD’s budget shrank substantially.

Not surprisingly, state and local governments were unable to offset diminishing federal support. Making matters worse, as federal and local housing subsidy contracts expired each year, previously affordable apartment projects were converted by owner-investors to market-rate projects. Meanwhile, the need for affordable housing and financial assistance kept growing.

Compared with other jurisdictions, the District is disadvantaged in addressing affordable-housing challenges. The fixed amount of developable land in the District, coupled with stringent density and height zoning regulations, constrain the city’s physical growth, putting upward pressure on real estate values and downward pressure on affordable-housing production. The District also lacks any state support.

The District’s inclusionary zoning policy does require new multi-family housing projects to offer a designated percentage of below-market units. But compared with the city’s needs, the number of such units remains relatively small, and most low-income tenants still can’t afford the subsidized units mandated by law because their household incomes are still too low to afford the rents. Consequently, many subsidized units are occupied by moderate-income households.

Today, low- and moderate-income families face ever-worsening housing challenges. The residential marketplace offers increasingly fewer affordable housing options. Rents and homeownership costs continue to rise, consuming an increasing percentage of household income, while leaving less and less disposable income for basic household necessities.

The National Low Income Housing Coalition reported this month that, throughout the United States, low-income workers in minimum-wage jobs cannot afford a modest, two-bedroom apartment or, in places such as the District, even a one-bedroom apartment. At the same time, the number of low-wage, service-sector jobs and workers will continue to increase.

Voters and taxpayers, not government officials and agencies, are ultimately responsible for failing to meet today’s undeniably difficult housing affordability challenges. Most Americans are unable or unwilling to shoulder the additional economic burden — taxation — required to pay for housing subsidies. This is why the lawsuit filed by Aristotle Theresa will do little to solve the District’s affordable-housing problems.

Roger K. Lewis is a retired practicing architect, a professor emeritus of architecture at the University of Maryland and a regular guest commentator on “The Kojo Nnamdi Show” on WAMU (88.5 FM).