Welcome to the CEHTP Geocoding Service.
Due to changes in CEHTP’s program objectives and resource limitations, we have been partnering with CDPH’s Information Technology Services Division (ITSD) to identify and transition to an alternate geocoding service for the Department. CEHTP no longer supports the desktop geocoder, and we will be discontinuing our entire suite of geocoding services by 2015. If you are a CDPH employee, consultant, or partner, please contact ITSD to learn about the new CDPH geocoding service. For more information, please contact the geocoding administrator.
The California Environmental Health Tracking Program (CEHTP) developed a suite of geocoding tools to assist organizations 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).
The CEHTP geocoding service is:
- Accurate- It uses multiple commercial and public geocoding reference databases, such as real property centroids, street centerlines, and zip+4 centroids. It also uses other geocoding services, such as Google and Yahoo's geocoders. Learn more.
- Complete- The service commonly provides 96-98% match rates within its suite of geocoding reference databases. Learn more.
- Fast- In batch mode, the tools can geocode about 300,000 records an hour. Learn more.
- Secure- Secure Sockets Layer (SSL) encryption is used when addresses are submitted to the geocoding service. For CDPH employees, the tools are entirely within the local network. Learn more.
- Tested- CEHTP geocoding services have been used by a number of CDPH programs and partner organizations. 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 using this demonstration. We strongly recommend that read "What should I know before geocoding?" in the FAQ section.
CEHTP offers a number of tools in its geocoding service suite. "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): Please note that CEHTP no longer supports this application
- 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)
To explore some of the capabilities of the CEHTP geocoding service, go to the demonstration of a single address geocoder. You do not need to be registered to view the demonstration.
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 the CEHTP website when reporting results. To request additional geocoding service, please contact the geocoding administrator.
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. During geocoding, a geographic information system (GIS) software matches each record in a database with the geographic reference files. Geocoding is also called georeferencing.
Geocoding is essential for many reasons. Georeferenced data can be useful for visualization, such as mapping locations where events of interest occur. Geocoding is also often the first step in linking environmental and health data for a variety of public health purposes, such as research and surveillance.
Even though geocoding has become a basic activity in public health practice, some organizations still do not have geocoded data while others may have data that are incompletely geocoded. For example, some programs may not realize that their data may become more useful if georeferenced. Others may lack expertise or resources for geocoding, as geocoding may be expensive. CEHTP’s centralized geocoding tool offers high-accuracy geocoding at no cost.
Geocoding is an important tool that can be useful to people from a variety of backgrounds and interests. However, without some basic training and awareness of certain limitations, geocoded data can be misused, leading to undesirable results. To ensure that data is geocoded, interpreted, and handled properly, please consider the following:
- How well do you understand the data you are about to geocode?
- Are you creating maps that will identify people's homes? How 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 or geographic scales? We strongly recommend that read "What should I know before geocoding?" in the FAQ section.
- 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. Please note that CEHTP no longer supports the desktop geocoding application. We welcome your comments and feedback.