by Cory Martin, Lead Developer on July 14, 2010 at 1:48PM
There are over 130,000 public and private schools in the United States. Currently, the most comprehensive list of schools is maintained by the National Center for Education Statistics (NCES)—but even this source is far from perfect in terms of completeness and accuracy.
Firstly, although public schools are required to report to the NCES annually, depending on when changes (e.g. new or consolidated schools) occur and the fact that the NCES generally does not publish results until about a year after the reporting cutoff, some of its data can be as much as two years old.
Further, around 2000, the NCES added lat/long coordinates for the schools in its databases by geocoding the schools’ addresses against TIGER and perhaps another street dataset. However, we find that the placement of many of these schools is considerably off, many miles in some cases.
As I’ve described in previous posts in this blog series, for Maponics School Boundaries, we annually source and update the entire set of school geography (including school district boundaries, school attendance zones and school locations and profiles) for every locally-sourced area. Under our Maintenance Program, we revisit and verify the district’s information each year. As part of this process, we work with local resources and officials to ensure that we represent the latest information about all the schools within the district.
We start with the NCES database and state lists and then go directly to the school districts to ensure we represent all public schools in our data and know where they are located. We geocode any addresses obtained against a high-quality dataset and take any locally-sourced point sets and update these using aerial and satellite imagery to move the point to the rooftop of the school.
Of course, with Maponics School Boundaries, the value comes not just from the comprehensive database of schools but the combination of the database with the related boundaries, including school attendance zones and school district boundaries.
by Cory Martin, Lead Developer on July 8, 2010 at 10:08AM
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.