Second, the corresponding Floor Area Ratio (gross floor area divided by land area) of all properties built within each decade:
It's important to remember that the Assessing data only contains properties that continue to exist to this day, so anything demolished would not be recognized in this data set. I also noticed that in older properties, year of construction was sometimes rounded off to the nearest decade. And it's possible there are other errors. I had to correct a few more egregious and obvious ones (like fields being swapped), but more subtle errors could sneak by. Condos are handled by summing up the gross floor space for each unit and linking it to the land area used up by the overall building.
Without spending too much time on analysis (that's for later), I'll note that we live in a turn-of-the-twentieth century city: most of the floor space created and still existing seems to have occurred between 1890 and 1930. The 1930s and 1940s had some fairly obvious reasons for a lull, but construction never really picked back up afterwards at the same rate. My hypothesis: Zoning in its modern form was enacted in the mid-1950s, which has put a heavy damper on construction ever since.
The FAR chart shows that development generally hovered around 1.0 floor area to land area, but started to drop precipitously after 1930, until finally tanking at a miserable 0.21 during the 1960s. Although the amount of floor space developed increased from the 1950s into the 1960s, the amount of land area consumed zoomed up even higher. Zoning could explain some of it,
For the curious reader, here is the result of summing over all the parcels in the database:
- Boston parcels gross area: 651,202,719 s.f.
- Boston parcels land area: 1,268,597,774 s.f.
- Boston parcels FAR: 0.51