Geocoding Service

About our service

The California Environmental Health Tracking Program (CEHTP) developed a suite of geocoding tools to assist programs in standardizing, verifying, and geocoding address data to latitude/longitude coordinates and other political boundaries (e.g. Census Blocks, Medical Service Study Areas, Public Land Survey sections, or Zip Codes).

Our geocoding service is:

• Accurate- We use multiple commercial and public geocoding reference databases, such as real property centroids, street centerlines, and zip+4 centroids. We also use other geocoding services, such as Google and Yahoo's geocoders. Learn more.
  
• Complete- We commonly experience 96-98% match rates with our suite of geocoding reference databases. Learn more.
• Fast- In batch mode, our tools can geocode about 300,000 records an hour. Learn more.
• Secure- We use Secure Sockets Layer encryption when communicating with servers.  For CDPH employees our tools are entirely within our local network. Learn more.
• Tested- Our services have been used by governmental, academic, and non-profit programs, including the California Health Interview Survey, the California Sexually Transmitted Disease Control Branch, the California Vector Borne Disease Section, Oakland Berkeley Asthma Coalition, and UCLA School of Public Health. Learn more.
• Free- The services available here are free. See registration and use for more information or register here.
  

Learn more about geocoding, why it is important, and how it can be used. Explore the single address geocoder for a demonstration.

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Choose an access tool

CEHTP offers a number of access tools to our geocoding service. "Batch geocoding" means to geocode multiple addresses that are in a data file.

• Batch geocoding for non-confidential data  (browser-based application, registration required)
• Batch geocoding for confidential data  (desktop application, registration required)
• Incorporate geocoding into a desktop or web-based application  (web service APIs, registration required)
• Geocode a single address  (use our demonstration tool, registration is not required)

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Demonstration

To explore some of the capabilities of our geocoding service, go to our demonstration of a single address geocoder. You do not need to be registered to view the demonstration.

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Registration and Use

The geocoding service is free for California Department of Public Health (CDPH) employees and partners. Please register to get an account. We request that you cite the California Environmental Health Tracking Program or link to our website when reporting results. To request additional geocoding service, please contact the geocoding administrator. 

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What is geocoding?

Have you ever used an internet mapping site like Google Maps or MapQuest to map an address? If so, you have already geocoded. 

Geocoding is the process of finding the geographic coordinates associated with a location such as an address or zip code. Geocoding can be useful for many reasons. Geocoding data can be useful for visualizing data (e.g. mapping locations where events of interest occur). Geocoding is also often the first step in linking environmental and health data for research.

There are a number of reasons why a program may not have data that has been accurately geocoded. Some programs may not realize that their data may be more useful if geocoded. Other programs may lack expertise or resources for geocoding, as geocoding can be expensive.  Some programs may have inaccurately or incompletely geocoded data.  With our centralized geocoding tool, CEHTP offers high-accuracy geocoding at no cost.

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Responsible geocoding

Geocoding is an important tool that can be useful to people from many backgrounds and interests.  However, geocoding data can be mishandled due or misused to lack of awareness or training.  To ensure that data is geocoded, interpreted, and displayed properly, please consider the following:

• How well do you understand the data you are about to geocode?
• Are you taking steps to ensure confidentiality?
  
• If you are mapping the geocoded data or comparing it to other geographic data, have you accounted for differences in coordinate systems?
  
• Are you creating maps that will identify people's homes?

For more information, view the checklist for responsible geocoding.

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For assistance and more information

• FAQs - View our Frequently Asked Questions to learn more about our geocoding services.
• Instructions and Tutorials - View step-by-step instructions for using the geocoding services, technical FAQs, and more.
  
• Geocoding Group - Join our geocoding service Google Group to view or submit questions and answers about our geocoding service and tools, and receive real-time updates about the service.
  
• Technical References - For more technical information about geocoding services, including software references, algorithms and architecture.
  
• Other resources- View publications and websites about geocoding.
  

For more information, contact the geocoding administrator.  Please notify us of any problems with our services.  We welcome your comments and feedback.

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