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14 <br /> 1 <br /> 2 Staff has provided a map as Attachment B summarizing the party affiliation for current voter <br /> 3 registration countywide and by the two current Commissioner electoral districts. <br /> 4 <br /> 5 3) Can staff review the annual population projections published by the American <br /> 6 Community Survey (ACS) and provide information on the population trends for <br /> 7 both Commissioner districts - since the 2010 Census - in anticipation of the 2020 <br /> 8 Census? <br /> 9 <br /> 10 Staff reviewed 2010 Census data and the most recent population estimates from the American <br /> 11 Community Survey. The 2010 Census detailed population numbers are based on more precise <br /> 12 block level delineations (Attachment C). Conversely, the ACS develops its population <br /> 13 projections at a larger block group level, with each block group consisting of multiple Census <br /> 14 blocks (Attachment D). The block group areas in some cases consist of land areas larger than <br /> 15 the towns in the County. Additionally, while block boundaries align more directly with the <br /> 16 Commissioner electoral districts, the larger block group level boundaries vary substantially from <br /> 17 the current Commissioner electoral district lines. <br /> 18 <br /> 19 The ACS 5-Year estimates utilize 5 years of collected data to produce estimates based on the <br /> 20 block group level. It should also be noted that the ACS data are only estimates based on <br /> 21 sampling and are not as accurate as the decennial Census data. For example the 2010 <br /> 22 Census population for Orange County was 133,801. Conversely, the 2010 ACS (5-year), a 5 <br /> 23 year period prior to the 2016 ACS, estimated the County's population at 129,562. This equates <br /> 24 to 3.22% lower than the actual 2010 Census. The 2016 ACS may similarly underrepresent the <br /> 25 2016 population, but is statistically relevant. <br /> 26 <br /> 27 Using the 2016 ACS 5-year data (the most current data available from ACS), staff developed <br /> 28 estimates of the population for the two BOCC voting districts. Unfortunately, as noted <br /> 29 previously, the block group boundaries do not follow the current BOCC electoral districts (figure <br /> 30 1). There are six block groups that are split by the voting districts. <br /> 31 <br /> 32 Figure 1 <br /> 33 For each block group that was entirely within a single BOCC voting district staff assigned the <br /> 34 population numbers to that voting district. For three of the block groups that were split, staff <br /> 35 utilized the County's current address layer to calculate how many residential addresses were in <br /> 36 each block group. Staff subsequently took the percentage of addresses for each block group <br /> 37 that were in each voting district and then divided the total population for each block group by <br /> 38 the percentages and then assigned the population numbers to each district (figure 2). This <br /> 39 allowed staff to estimate the 2016 populations for each BOCC voting district (figure 3). For the <br /> 40 other three split block groups that had only a small percent of addresses in a district, staff <br /> 41 applied the entire population to the district that had the majority of addresses. <br /> 42 <br /> 43 Figure 2 <br /> 44 To summarize, the 2010 Census population for District 1 was 82,412. The County staff <br /> 45 generated 2016 ACS 5-Year estimate for District 1 is 85,990. <br /> 46 <br /> 47 The 2010 Census population for District 2 was 51,389. The County staff-generated 2016 ACS <br /> 48 5-Year estimate for District 2 is 53,817. <br /> 49 <br />