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Archive for the 'geocoding' Category Page 2 of 2

The Geocoding Database

The Geonames website offers a number of useful geocoding services:

  • Enter a name, and get back:
  1. A list of the first fifty geographic features in their database that include that name
  2. The feature coordinates
  3. A link to let you plot the location of that feature in Google Maps, along with fifty other nearby features
  4. Links to download those features in “csv” spreadsheet format (looks more like tab-delimited to me), or a png image that shows the selected feature plotted as a red point on country line graphic:


  • A web-based geocoding service
  • A postal-code lookup service
  • A downloadable copy of the geocoding database, by individual country, or combined into a single 150 MB file for all countries

Convert A Google Maps Point To Multiple Text Geographic Formats

There’s a handy Google Maps site that lets you place a marker, gives you the position, and then lets you convert that position into a number of geographic text formats.

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Another Google Maps Geocoder/Reverse Geocoder

An earlier post covered a Google-Maps-based reverse geocoder, where you could click on the Google Map interface, and get a list of addresses close to that point. Reverse Geocoder for the United States is another Google-Maps-based application in the same vein. While it doesn’t have as many features as the Geonames reverse address geocoding site, it uses the Google Maps interface better, with a larger map display (one of the largest I’ve seen online) and the sliding zoom control (missing from the former site).

It’s easy to use: click on a point on the map, and you’ll get a marker placed there, and the latitude/longitude displayed in a box at the upper right. Click on “Submit point”, and the closest addresses to the selected point will be displayed as markers on Google Maps, and in a list on the right. Click on an address on the right, and a marker balloon will pop up on the map at the corresponding address. It also gives you the Zip+4 postal zip code for the address, which the Geonames site doesn’t. You can also enter a latitude and longitude in the upper right separated by commas, submit the point, and get similar results. A companion site does geocoding – submit an address, get back the latitude/longitude, and the address plotted in Google Maps (make sure you include either the city/state or zip code in the entered address).

Coverage is limited to the lower 48 US states and Alaska. Geocoding seems to use the Tiger database, whose accuracy varies depending on location.

Public Land Survey Systems (PLSS) Shapefiles And Geocoding

If you need to identify a township or section on map, or plot Public Land Survey Systems (PLSS) boundaries, you can get this data from the Land Survey Information System website, managed by the BLM. Shapefile data is available for most of the US, grouped by state and/or county, in the NAD83 datum. File data includes township, section, subsection, latitude/longitude, and metadata. Note: Make sure you have pop-ups enabled.

There’s also a Township Geocoder web form. Enter the latitude and longitude of the point you’re interested in, NAD27 or NAD83, and get back the state, principal meridian, township, range, section, quarter section, and quarter-quarter section. Or enter the previous data, and get back a latitude/longitude. You can enter individual points, or upload a file for batch point conversion.

Another Free Excel Geocoder

Stumbled across another free Excel spreadsheet that uses the Yahoo geocoder to convert addresses to geographic coordinates. Simple, basic, but does the job.

A link to a compressed version of ExcelGeocoder is available at the top of this page. Run the program to uncompress the spreadsheet, then open it up in Excel. It requires Visual Basic for Applications, so it won’t currently run in OpenOffice, but apparently VBA compatibility is coming soon to OpenOffice’s Calc spreadsheet and other components.The program uses Yahoo’s Geocoder, and requires you to enter a Yahoo ID in the Settings And Instructions tab, a remainder from when you had to register to use the service. Since registration is apparently no longer necessary, you can enter anything you want for a Yahoo ID, but you have to enter something. Paste your address data into the appropriate columns in the spreadsheet, click on the Geocode button in the upper left, and you’ll get back latitude/longitude for those addresses (up to 5,000 per day is allowed by Yahoo).

If you want to use this geocoded data in Google Earth, you can use excel2kml, or if you save the resulting data in CSV format, you can use csv2kml to convert it into a Google Earth file. You can also convert it into a point shapefile using software that I’ll be covering soon.

Reverse Address Geocoding With Google Maps

Geocoding is the assignment of geographic coordinates to a location, typically one identified by name or address. I’ve covered address geocoding in an earlier post, in connection with converting US addresses to points in a KML file for use in Google Earth. Reverse address geocoding refers to finding the address closest to a set of geographic coordinates, and I’ve found a website/webservice that will do this for US addresses.

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US Address Geocoding For Google Earth

Geocoding is the process of assigning geographic coordinates to locations designated by some other parameter, like name or address. Google Earth Plus lets you geocode up to 100 US addresses in spreadsheet form, assigning them a location. But there are a number of tools that can do this for free, and in some cases allows you to process more than 100 addresses at a time.

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Importing Spreadsheet Data Into Google Earth

One of the features offered by Google Earth Plus is the ability to import data in spreadsheet format, specifically the CSV format: Comma-Separated Values a simple text format where data values are separated by commas, and each set of data is in a different line. But Google Earth Plus has a limit of 100 points for data import. When you consider that there are free options that will convert spreadsheet data into Google Earth’s KML format without this size limitation, then it’s not all that much of a “Plus”.
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