I've started working on a project with a huge number of polygons, and I'm unsure of how to display/host it. The map I'd like to end up with will have three layers:

1) Shaded polygons representing each of the 70K+ U.S. census tracts. I currently have this as both a shapefile and a spqllite file in Tilemill.

2) Another 15K points representing locations on roadways (this layer will be interactive)

3) A street layer, such as OpenStreetMap

I would set the opacity of the first layer so that the street layer remains visible. I've looked at possibly using UTFGrids, but haven't found much documentation.

Any ideas on how I might want to implement this one?

UPDATE: I'd prefer to use TileMill, but am open to different platforms.

  • Welcome to GIS SE! Would you be able to edit your question to clearly state whether SQLite, TileMill and OpenStreetMap (as well as the unmentioned but tagged ArcGIS and MapBox) are requirements of your solution, please? At the moment I think it is too broad but if you can nail down some more of the requirements then it starts to look more like it fits the parameters of our site.
    – PolyGeo
    Commented Jul 23, 2014 at 3:59
  • If you are open to different platforms, you may want to take a look at GIS Cloud. Their HTML5 Canvas implementation is able to handle huge datasets: directionsmag.com/articles/… Commented Jul 23, 2014 at 12:22

1 Answer 1


To display that many polygons, you'll almost certainly need to use a tiled layer, rather than streaming the vectors to the client.

You've tagged this with ArcGIS, so you could use ArcGIS for Server or ArcGIS.com to generate a tiled layer, which could be shown in the ArcGIS JavaScript API. You can display this tiled layer with the OpenStreetMap basemap layer, and apply a transparency.

15k interactive points will probably slow your browser down, so you could consider creating a cluster layer from them.

  • Thanks; I'd definitely prefer to use a tiled later. I don't have ArcGIS for Server (only ArcGISDesktop Advanced). Is there another way to generate the tiled layer?
    – Mike
    Commented Jul 23, 2014 at 13:32
  • @Mike you can use ArcGIS Online, which allows you to pay using credits (rather than having to purchase a full Server license). You can sign up for a free Developer account to test it out - you'll only pay if you actually deploy it Commented Jul 23, 2014 at 23:40

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