I have found GIS shape files from the following link: http://elections.il.gov/votinginformation/2011congressionaldistricts.aspx What would be the easiest way if possible to process/tool that I need so that we can map/lookup the list of zip+4 codes to the shapefiles to find the senator and representatives name, address, zip, district and county.

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    -1 - Please add more detail, ie, GIS software you have to use, the ultimate goal of the project. It seems there is more data you need first. The shapefiles are not downloadable from that site, you have to contact the office to obtain them. You need a layer of zip+4 codes to work with. Right now, the last sentence of your question is very confusing, please break it down for us. – Get Spatial Aug 24 '12 at 21:11
  • I have called this number 212-782-4141 and they are sending us the shapefile CD via mail. I have a list of zip+4 codes. I have to map the zip+4 code to district,legislators and Senators. So the output file will have zip+4, names of the legislators and Senator, addresses of them, district and county. At this time I do not own any GIS software and would like to know what to use to succeed on this project. – Chitrarekha Saha Aug 24 '12 at 21:22

For some sense of why folks aren't thrilled about your question check this thread: Looking for ZIP+4 boundaries

Zip codes--especially the nine digit variety--are not easily transcribed in the way you would like (They aren't polygons and the routes frequently cross district borders). One approach would be to use 5 digit zip codes (see also Sources for US Zip Code Boundaries?) which might be a bit better (although some 3000 zip codes cross district boundaries nation-wide). Even then, you still basically need someone to just do it for you since you have no software or software familiarity.

For what it is worth, what you are asking for is possible in R, QGIS, GRASS and several other open source projects, but with your level of knowledge it is likely more efficient to simply purchase a database. Search "zip codes by congressional district" for multiple options. I found the summary here: http://askville.amazon.com/Easy-free-online-identify-zip-codes-Congressional-District/AnswerViewer.do?requestId=14537568 to be sufficient.

Given the simplicity of putting together this file in rudimentary form someone may be inspired to make a free version (it might even be me), but for now you are stuck I think.

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