Links: New data set from city shows free digital maps of Ann Arbor and Washtenaw County
Part of the release of new data sets from the City of Ann Arbor is a set of maps, in digital form. Here's a view of each of them, so that you can see what's there and how you might use them in your own mapping efforts.
The maps are provided in two formats: a KML format, which is usable by Google Earth, and a shape file format, which is usable by GIS programs. KML is also readable within several online map systems like Google Maps, and the examples I will show will come from that.
The most basic of all of the maps is the Ann Arbor city boundary map, which shows the current boundaries of the city. You will note that there is a very ragged edge between the city and surrounding townships, and there are a number of township islands inside the city limits.
City of Ann Arbor, Google Maps
Plans under review
The city publishes a feed of Petitions Under Review, showing requests for approval from city departments for construction and development.
City of Ann Arbor | Google Maps
From time to time on the agenda of the City of Ann Arbor, Pittsfield Township, Scio Township or Ann Arbor Township you will see annexation requests, which will change municipal boundaries as a result.
School district maps
A third very useful set of county wide maps are boundaries of school districts and townships, seen here combined on one map.
City of Ann Arbor, Washtenaw County GIS
Township islands within the city of Ann Arbor
The irregular boundary of Ann Arbor creates township islands, parcels which have not been annexed to the City in the course of its growth.
City of Ann Arbor AAGIS
What it means for maps to be free
When these maps were originally released, they had a copyright notice on them which restricted them to internal use; that copyright was amended. The school district map detail page says:
"This feature dataclass was created with the intentions of displaying all of the school districts who's boundaries are located within Washtenaw County. The boundaries were created by dissolving the current Washtenaw County parcels layer by the school district field. In order to maintain the attributes of the old school districts file, we then lined up the boundaries from the old school districts map with the dissolved layer. After the boundaries were lined up, topology was created in order to verify that there were no topological errors within the feature dataclass."
Map-making can be hard work; there are a lot of details to get right.