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i bt e9of30 WiwW an February 28, 2019 To: Alex Khojikian Fr: Douglas Johnson & Shalice Tilton Re: Whipple Avenue alignment problem Attachment B A problem in the Census Bureau's geographic data led to the assignment of Councilmember Reddy to the wrong district in some of the draft maps under consideration by the City and Council. We apologize for not spotting this very rare and unfortunate problem, and this memo describes what happened and how it is being corrected. To understand what happened, first a bit of background on the Census is necessary. Every ten years, the Census Bureau compiles the "Master Address File." This database contains every residential address in the country, and each of those addresses is assigned to a Census Block roughly based on the city block (bounded by four streets) where the house is located. A census form is collected from every one of those addresses, and the population reported on that form is counted as part of the population of that Census Block. It is worth noting that no maps are involved anywhere in this entire process: even the Census Block is identified as something like "the left side of Whipple Ave, the right side of Nevada St, the right side of Hopkins Ave and the left side of Hillview St." The Census Bureau maintains a "geocoder" website, where anyone can look up any address and see its Census Block assignment from this database, and that represents the official assignment of population for equal population purposes, and typically that represents the ultimate way a jurisdiction confirms whether an officeholder or candidate resides in or out of an election district. Again, there are no maps involved at this stage. Once the Census population data is compiled for each Census Block, the Census Bureau reports that data out to the world. And the Bureau matches that data with a separately -compiled map of those Census Blocks. This map was originally compiled back in the 1950s, 1960s and 1970s by digitizing streets from old United States Geological Survey (USGS) maps. In the 1980s through 2010, the Bureau attempted to update those maps by collecting street maps from local jurisdictions and digitizing them. But sometimes those digitizing efforts, especially the automated attempts to process USGS maps, go awry, and that is what happened here. As you know, Whipple Avenue in this part of the city runs straight from the northeast to the southwest. But the Census Bureau's digitized maps thought it took a bizarre hard left and then hard right turn. Below are the maps showing (on the left) the actual Whipple Ave and (on the right) the Census Bureau's version: Phone: (818) 254-1221 P.O. Box 5271 info@NDCresearch.com FAX (818) 254-1221 Glendale, CA 91221 www.NDCresearch.com 204