Updated annually in July
The main components of population change are births, deaths, and migration.“Natural increase” is defined as the difference between live births and deaths.“Net migration” is defined as the difference between the number of people moving into an area and the number of people moving out.For OFM’s annual population estimates, it is more permanent movement that is of particular interest (i.e., not seasonal or temporary).Because it is difficult to measure actual migration, demographers often estimate migration as a residual value, by calculating the difference between total population change and natural increase.
Components of April 1 population change
Example computation of residual migration for 2000 to 2010
| 1. Clark County 2000 federal census population | 345,238 |
| 2. Clark County 2010 population estimate | 425,363 |
| 3. =(2)-(1) Clark County population change 2000-10 | 80,125 |
| 4. Clark County births 2000-10 | 55,706 |
| 5. Clark County deaths 2000-10 | 25,968 |
| 6. =(4)-(5) Clark County natural increase 2000-10 | 29,738 |
| 7. =(3)-(6) Clark County residual migration 2000-10 | 50,387 |
Additional sources of migration data
