St. Louis is in the midst of a senior housing boom, driven by baby boomers who are just now old enough to demand that kind of specialized multifamily housing in great numbers.

In the last 18 months, at least six assisted living communities have completed or have started expanding their assisted living and skilled nursing offerings, the St. Louis Post-Dispatch reports. These projects are worth about $230M.

The reason is straightforward — supply and demand. The nation as a whole has a graying population, and St. Louis is especially skewed toward an older demographic.

About 15% of metro St. Louis' population is 65 or older, according to the Census Bureau, which is the eighth-highest concentration of that age group for any U.S. metro. By 2045, 25% of the region's population will be over 65.

Examples of new senior housing in St. Louis are plentiful. In early December, FV Services Inc., a nonprofit that operates Friendship Village Sunset Hills and Friendship Village Chesterfield, announced a $200M project adding hundreds of units along the continuum of care to both campuses.

The Gatesworth, a high-end senior living facility in University City, early in the month completed the first phase of its McKnight Place assisted living and skilled nursing remodeling project. That added 90 new assisted living units.

New companies are coming into the St. Louis market as well. Stonecrest opened 160 assisted living and skilled nursing units in the last 12 months, and it is working on an 81-unit facility in Wildwood. Chicago-based Senior Lifestyle has built three new assisted living and skilled nursing facilities in the last two years.