Much like the rest of the United States, the wealth in California is highly concentrated among a small percentage of of high-income households.
California had roughly 16 million households in 2014, and just 0.4 percent of them (61,000 total) combined to account for 20 percent of the state's income, per The Sacramento Bee according to tax return data from the Franchise Tax Board. As you can see from the interactive map above, a large percentage of those households are located in the San Francisco Bay Area.
Not coincidentally, the three least affordable California counties are located directly within the highest concentration of high-income households. During the third quarter of 2016, approximately 31 percent of California households could afford to purchase a median-priced single-family home, according to the California Association of Realtors.
However, the state's three most expensive counties - Marin (19%), San Mateo (15%) and San Francisco (14%) - fell far short in the CAR affordability index.
The median home prices in those counties were the highest in the state: Marin ($1,225,000), San Francico ($1,375,000) and San Mateo ($1,330,000).
The in-affordability throughout the Bay Area for median-priced homes among many households only fuels the continued growth of nearby counties as homeowners relocate to surrounding communities.
Case in point is Sacramento County, where the affordability index is 45 and the median home price is $323,710. Home prices have increased 9.7 percent over the past year and are projected to increase another 5.4 percent during the next year, according to the Zillow Home Value Index. It's a similar scenario in Yolo County, where the average price is $381,250, home values are up 8.1 percent year-over-year and expected to grow 4.7 percent over the next year.
That's a drastic difference that has already gained the attention of many savvy buyers.