About Mapping L.A.: Neighborhoods

Los Angeles is a city that remakes itself constantly, so drawing boundaries for communities can be perilous. City officials are happy to designate community names, but have never been willing to set borders. But, with your help, we at The Times have done just that.

Why draw lines? Consistency is one reason. If we report that an event occurred in Van Nuys or Westwood, we want people to know exactly where we mean. Beyond that, defining boundaries will allow us to give our readers a wealth of data, about demographics, income, crime, schools and more, for specific geographical areas.

The initial cut of Mapping L.A.'s neighborhoods was based on census tracts. These areas, drawn by the U.S. Census Bureau for tabulating demographic information, allow us to compile statistical profiles of L.A. communities. Unfortunately, they are frequently out of sync with the geographical, historic and socioeconomic associations that define communities.

Consequently, we’ve adjusted the lines in many cases. We’ve done so by moving individual city blocks from one census tract to another. In each instance, we’ve adjusted the census data in proportion to the population of each block.

Because L.A. is always changing, Mapping L.A. will change with it. As communities gain in size or importance, or diminish, we’ll reflect those changes in these maps. But, the boundaries we recognize today will not be lost. Every time we move a city block from one community to another, we’ll keep a record of the original map that can be republished any time it’s needed. We’ll also keep a log of changes on the site for use by anyone seeking to trace the city’s evolution. We’ll also keep a link to the prototype version of the map as it was first published in February

To put these maps on your computer screen, we’ve had to simplify the complex electronic shapes. Essentially, these maps consist of points with lines drawn between them. Lots of points are needed to conform to irregular boundaries such as streets. We used the Douglas-Peucker algorithm to reduce the number of points for better online performance. This can lose precision in the online presentation, but is necessary to accommodate users with older computers or browsers.

This site is built entirely with free and open-source software, including Django, jQuery, OpenLayers and PostgreSQL. Thank you to all of the community members who have contributed to their development.