The Internal Revenue Service (IRS) provides data based upon year to year tax return addresses that reveals the from and to locations when people move.
According to recently released IRS 2014-2015 tabulations, nearly 77,000 households in Whatcom County remained in the County, just over 5,500 households (~7%) moved into the County and just over 4,600 (~5.5%) moved out of the County.
In terms of adjusted gross income, those moving into Whatcom County represented $323,881,000 and those moving out represented $231,704,000. So the adjusted gross income increased $92,177,000 as a result of migrations in and out as reported by the IRS.
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Click for more informationThe following table shows the top 10 most popular destinations for those moving out of the County (in order of # of people).
| Destination | Households | People | Income |
| King County | 762 | 986 | 35,595,000 |
| Skagit County | 459 | 765 | 22,244,000 |
| Snohomish County | 419 | 672 | 18,248,000 |
| Pierce County | 139 | 220 | 5,790,000 |
| Maricopa County (AZ) | 100 | 191 | 5,245,000 |
| Spokane County | 82 | 131 | 2,877,000 |
| Thurston County | 72 | 120 | 3,223,000 |
| Clark County | 70 | 109 | 4,075,000 |
| Los Angeles County (CA) | 66 | 100 | 3,241,000 |
| Multnomah County (OR) | 70 | 87 | 1,770,000 |
The following table shows the top 10 origins for those moving into the County (in order of # of people).
| Origin | Households | People | Income |
| King County | 832 | 1259 | 49,183,000 |
| Skagit County | 428 | 765 | 20,288,000 |
| Snohomish County | 456 | 755 | 25,021,000 |
| Pierce County | 153 | 232 | 5,971,000 |
| Maricopa County (AZ) | 88 | 187 | 7,517,000 |
| Island County | 120 | 183 | 3,904,000 |
| San Diego County (CA) | 91 | 177 | 6,181,000 |
| Los Angeles County (CA) | 92 | 149 | 5,657,000 |
| Spokane County | 99 | 134 | 3,941,000 |
| Thurston County | 80 | 112 | 2,003,000 |
The 4 closest counties, Skagit, Snohomish, King and Pierce, take the top 4 positions for migration both in and out of the County. Next on both lists is Maricopa County, home to Phoenix, AZ, followed by other Washington, Oregon and California counties.