School Geography: How School Attendance Zones (SAZ's) Get Their Shapes
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Local school boards generally establish where students attend public schools—and they do so by defining a geographic area (often called a school attendance zone) of residences associated with each public school. Some school districts have only one school for each grade range, so their SAZ's are coextensive with the school district boundaries. But most school systems operate more than one elementary school, middle school or high school. In order to balance the number of enrollments and the needs of the student population with available space and resources, school boards establish school attendance zones.
As I discussed in my last post in this series, school district boundaries change to reflect underlying demographic shifts and numerous other social, economic and political factors. Well, school attendance boundaries are even more likely to change for two primary reasons:
- By definition, schools attendance zones are established and adjusted to balance student populations within school districts and as a result, they often change over time even when school district boundaries do not: and
- Schools attendance zones are directly associated with school locations themselves—geographically, they are represented as a boundary around a single school. So, as schools are created, expanded or closed, school attendance zones change.
For example, in Frisco, Texas, where I happen to live, significant population growth means that school attendance zones may have to change almost every year for the foreseeable future.
How We Source and Build School Attendance Zones (SAZ's)
Neither the federal government nor most states maintain a school attendance zone boundary set. These have to be sourced from the local school districts. This is a daunting task in that there are almost 14,000 US school districts with school attendance zones and they record these boundaries in a variety of formats—many of which are not in high-quality digital maps.
We go directly to local authorities to collect all sorts of resources to define the limits of the SAZ's. Sometimes we are able to acquire digital map data, but most often districts only share paper maps, low quality PDF's, or provide a list of school assignments by address range. We take all of this raw data, import or digitize it, clean it up, make it all match up with street centerlines, satellite and aerial imagery and other school districts borders and attendance zones. Now imagine repeating all of this 14,000 times and updating them annually!
But, we understand the value in doing this because so many decisions, from real estate purchases to public policy to direct marketing, can be driven by defining a clear and consistent relationship between residences and public schools.