How many?

Yesterday one of my colleagues at the police department emailed me with a question. He wanted to know what number I use for Lincoln's population.  That's an easy one right now, as the 2010 Census data released earlier this year pegged Lincoln at 258,379.  The problem comes in between the dicennial censusus (censi?).  I'll see news articles, websites, and reports that will continue to use that 258,379 number clear up until 2021, when the next census numbers from 2020 are released.

I'll bet you could search through the City of Lincoln, State of Nebraska, and Lancaster County websites and find plenty of different numbers for Lincoln's population on pages and documents published at about the same time, so I counsel the consistent use of the best and most recent available population data. Right now, that's the 2010 Census count, but population is a moving target, and that count is just a snapshot in time. Lincoln's population is likely to change significantly every year during the decade.  Based on our historic rate, we will probably grow by somewhere between 35,000 and 45,000 during the next decade.

Thus, unless you want to use increasingly outdated numbers, you've got to make some kind of adjustment or estimate in between the decades.  If you live in a City of 100,000 or better, you shouldn't have to make your own guess, because every two years the United States Census Bureau releases fresh population estimates.  The methodology of the estimates is described in detail, and from my experience these have proven to be quite accurate when the actual tally is made at the end of the decade.

I recommend using the Census Bureau's most recent count or estimate because they are the authoritative source: not some city limits sign or some website with unattributed population data.  The every-other-year estimate is released in the summer of even numbered years, but it is an estimate as of July 1 of the preceding year.  The estimate is essentially one year behind, and always for the odd numbered year.  So next summer, the census bureau will release an estimate of Lincoln's population, but it will be an estimate of where that population stood on July 1, 2011.

By the way, think about the implications of Lincoln adding 3,500 to 4,500 residents annually.  In Nebraska, that's a pretty big town in its own right: somewhere around the size of Auburn, O'Neill, Fairbury, Cozad, or Broken Bow.  That's what we are tacking on to Lincoln, every single year.