The word "affordability" has been severely dumbed down by politicians of all stripes seeking to gain power and control. Affordability is not just the cost of things, it's mostly related to what people earn. Why are some areas of the US so much affordable than others? This requires more serious thought and evaluation.

Here are some factors to ponder:

• Housing is the largest factor, with coastal or desirable western states seeing high demand that exceeds supply, driving up prices. Rural areas and states with less population pressure often offer more affordable housing. Any politician who wishes to be taken seriously about affordability needs to propose serious, practical policies and incentives, not ideological band-aids that serve a few at the expense of all.
• States with a higher population density, or those in remote locations that require more expensive imports, tend to have higher costs of living.
• It's generally cheaper and more efficient to build infrastructure on flat land with no topography compared to uneven terrain, as it reduces the need for complex engineering, extensive excavation, and specialized materials. Florida is the flattest state in the US. California, Washington and Arizona have the highest elevation variation. Steep Slopes can lead to a 30%–100% increase in costs for building. 
• Most 'more expensive areas' have higher incomes too. These are the TOP 10 states that saw the biggest growth in median household income between 2010-2024:  Montana 42.9%,  Tennessee 41.6%, Kansas 37,1%, Maine 36,3%,  Massachusetts 34,6%, California 33,5%, Utah 32,1%, South Carolina, Washington DC and Georiga 32.6%, and Arizona 30,1%.  (US Census) Kentucky, Arkansas, Louisiana, West Virginia, and Mississippi have the lowest wages (under $65k median) in the US. Washington DC, Massachusetts, New Jersey, Maryland, Hawaii, and California have the highest, all with a median above $100k. These incomes often mirror housing costs.
• States that see a big influx of population may be cheap at first, but this can also fuel costs. While it fuels the coffers of those who own assets, it usually raises costs for all. Which US State gained the most population per capita?  South Carolina. The fastest per capita growth in the US, followed by Idaho and Delaware. Alabama and Maine each achieved very similar population growth per capita. A larger productive population can offset rising costs.
• Unions often drive up labor costs, but also deliver workers with incomes who are more capable of living without government assistance. Massive government assistance often attracts people from out of state, further fueling demand and costs to locals.
• Excessive government spending, scale, inefficiency, incompetence and regulation also drive up costs, especially when it slows down the construction of housing, thereby adding to supply constraints which is the chief driver of housing affordability.
• Good Weather attracts people. So do well-paying jobs. Good schools too. 
• Excessively high local taxes, crime, and/or corruption force people to move. When they do, those who remain have to pay more for less when services are cut, making things even less affordable.
• Some, not all, of the most expensive areas have the best schools. Often this results in high local taxation and higher living costs.
• Older States and cities have older infrastructure requiring expensive maintenance and repairs. Bad weather can make matters worse. Few politicians plan for 50-year results in 4-year election cycles.