The Wednesday post showed the Idaho 2010 Census at 1,567,582 and a growth of 21 percent which is 4th highest in the nation. Seven counties outpaced the state growth rate with Teton County on top followed by Canyon, Madison, Jefferson, Kootenai, Ada and Bonneville.
The change in population at the county level can help feed speculation on the potential impact on the redistricting of the Idaho Legislature. But to do that you have to make the following assumptions:
- 2009 county population estimates are accurate, and
- growth rates from 2009 to 2010 were the same across the counties, and
- there will again be 35 districts.
This entry builds on the early projections from three years ago. Bottom line is it appears one legislative district will have to give way among districts 1 through 9 and 22 to the Ada and Canyon county areas. Eastern Idaho districts 23-35 will need to shuffle some boundaries but collectively may remain similar unless Owyhee County is shifted into a district with Elmore County. At that point numbers may begin to favor another district in southwest Idaho.
Idaho’s constitution requires legislative districts to respect county boundaries except when needed to equalize populations. After the 2000 census the boundaries worked well in some parts of the state and less so in others, with some pretty crazy decisions for some districts (e.g. see District 31 that can be only traveled if one drive through Wyoming in part).
The following table was developed with 2000 census data and the 2010 statewide count with the 2009 estimates used to apportion the population by county.
In 2000 the 1,293,953 population averaged out to 36,970 people per district. In 2010 the 1,567,582 comes out to 44,788 per district. The first column shows how many districts were “deserved” by a county or group of counties in 2000 based on their population in relation to the average people per district, the second column shows how many districts were allocated and the third column shows the amount of districts “deserved” by a county based on their 2010 estimated population and 2010 average people per district. For example, Latah County had a 2000 census of 34,935 and was 94% of the target population for a legislative district. Nez Perce County had a population of 37,410 which was 101% of the target population. Both were awarded a single district shown as 1.00 in the Apportioned column. For 2010 both counties have slipped in proportion to the state population so their “Districts Deserved” declined to 86% and 89% respectively.
In many cases multiple legislative districts are combined for comparison because only county level data is available. The information is still useful because it shows that Districts 8, 9 and 22 are the ones that have shown the greatest drop in their ratio of population in proportion to the likely target population.
The five northern counties collectively are at 4.88 districts which divides into 96% of target population, close enough for only minor reshuffling. The declining ratio for Latah and Nez Perce can be taken care of by appending Clearwater to the former and Lewis to the latter. This leaves Idaho County to be combined with Valley, Adams and other areas to the south.
Any district, county or combination thereof where the ratio has fallen is shown in red. The ones with the greatest increase in the ratio are shown in green. In the latter case it is Ada and Canyon counties where collectively there is more than enough for an additional legislative district. The new district will come from cannibalizing Districts to the north.