San Diego: Natural Area Access

The Healthy Places Index dataset has a parkacess variable that measures, per census tract, the "percentage of the population living within ½ -mile of a park, beach, or open space greater than 1 acre". Here is a map of the variable over San Diego county:

Tract maps are a little hard to interpret, because the tracts are all different sizes, and there are a different number of people in each tract. Additionally, if you are trying to solve a social problem, what you really want to know is where should should build a new park; probably, you’d put it where there are a lot of people who are far away from parks. So, here is a different view, of the number of people per area ( square kilometer ) who do not have access to park land. This view shows higher values in areas that have a lot of people in a small area who have little access to parkland.

The yellow areas are the ones with the least park access, and the ones in the east side of the map are in El Cajon. Escondido in the north has a similar deficit. But the biggest surprise are the two yellow tracts in the middle, which are in North Part, close to Balboa. These tracts are just ourside of the 1/2 mile limit for the variable, and there are no other neighborhood parks nearby.