Using free geodata to check up on government plans

by Simon St. Laurent

Related link: http://simonstl.com/dryden/archives/000413.html



Thanks to free access to census and tax parcel data, I was able to calculate what the population densities are in a place that's been proposed to have a significant increase in density.



The U.S. Census Bureau provides an enormous amount of information about populations, down to relatively small areas. Unfortunately, the lines they choose for census blocks are somewhat arbitrary, especially in rural areas where the distances between roads can be substantial. The Census Bureau does align its blocks and tracts with municipal boundaries, but the areas I'm focusing on are unincorporated. New York State refers to them as hamlets, built-up places with an identity but no government specific to that area.



In this case, the Town of Dryden, which contains these hamlets, is working on a Comprehensive Plan. The plan suggests increasing the density of these hamlets to eight housing units per acre, but doesn't provide any baseline for what the density currently is. Figuring out that current density makes it much easier to have a conversation about what kind of change this means for the hamlet.



There are a couple of ways I could have figured this out. House-to-house surveys combined with surveying the areas involved was one option. Given the snow on the ground and the difficulty of showing up on people's doorsteps asking questions, it seemed better to use existing data from the census.



Census data is available for the entire country, but I'm extremely lucky to live in a county which makes vast amounts of GIS data available. Both the census data and the county's own maps are available through CUGIR, a GIS data clearinghouse for New York State. Having the tax parcel data available meant I could calculate areas that corresponded to the inhabited areas highlighted in the plan.



With the free data, I could calculate both populations for the hamlets, and, critically for the evaluation of this plan, their densities.



Free access to data makes figuring these things out much much easier.



Has free GIS data helped you figure out a community issue? Are there cases where you'd like to have more access to data for these purposes?