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Migration

July 2007

This site provides migration data and supplemental indicators of migration. Please note the cautions regarding these data for each selection. Migration is difficult to measure and migration is a difficult concept to understand.

• Measurement of population movement is always referenced to specific boundaries to determine "movers" and "non-movers."
• Measuring migration also requires criteria for determining the actual "residents" of a specific area. Some population movement is seasonal and temporary in nature. Migration is usually meant to reflect more permanent movement. In federal census data the actual residents of an area are defined in terms of "usual residence."
• Population gain or loss for a specific area due to migration is called "net migration." Net migration may be calculated by determining the number of persons moving into an area, or "in-migrants," and subtracting the number of persons moving out, "outmigrants." Net migration may also be estimated as a residual value and termed "residual migration."

For additional definitions and data please see the U.S. Bureau of the Census site on Geographical Mobility at: www.census.gov/population/www/socdemo/migrate.html.

For the rest of the states in the United States, please visit the Census Bureau's website at: www.census.gov/population/www/cen2000/ctytoctyflow.html

1. Population, Population Change, Births, Deaths, and Residual Migration 1960 to 2007 by County by Year (Excel®) Posted March 2004, annual update. CAUTION: These data show migration trends rather than absolute migration levels. As a residual value, the computed migration figure contains all of the error in the estimate of population change. The trends shown may not be reliable for smaller counties and counties with characteristics that make them difficult to estimate accurately. Erratic gains and losses are often apparent. Using a rolling average for three years of combined data might stabilize the migration estimates for smaller counties and those showing erratic trends.

Example Computation of Residual Migration for 2000 to 2007:

2. Migration between 1995 and 2000 for the State and Counties by Residence in 1995 from Census 2000 (Excel®) This table has several sections. The primary sections show the migration to and from the state and counties by age and gender. Migration is further cross-tabulated by source of in-migrants and destination of out-migrants. In-migrants to Washington come from other states and from abroad. In-migrants to Washington counties come from other states, other counties in Washington, and from abroad. Out-migrants from Washington go to other states. Out-migrants from Washington Counties go to other counties in Washington and to other states. The missing population movement in the data set is movers from Washington leaving the United States. Thus, these data probably overstate the net migration gains.

3. County to County Migration's Flow Between 1995-2000 (Excel®) These migration data come from the Census 2000 long-form question on residence 5 years ago and contain the number of people who moved between counties A data record was produced for every combination of county-to-county migration flows in the United States of at least one person between 1995 and 2000. Current county of residence is based on where the person was living on April 1st, 2000. Previous county of residence is based on where the person was living 5 years earlier. The file with two sheets are sorted separately by inmigrants to the state/county (inflows) and outmigrants from the state/county (outflows).

Inflow sheet: for each county in the state, the number of migrants who moved to that county from another county is listed. It contains records for FIPS state code in 2000, FIPS county code in 2000, county and state name in 2000 (current residence), FIPS state code in 1995, FIPS county code in 1995, county and state name in 1995 (previous residence), and the number of migrants who moved between those two counties (inflow).

Outflow sheet: for each county in the state, the number of migrants who moved away from that county to another county is listed. It contains records for FIPS state code in 1995, FIPS county code in 1995, county and state name in 1995 (previous residence), FIPS state code in 2000, FIPS county code in 2000, county and state name in 2000 (current residence), and the number of migrants who moved between those two counties (outflow).

Last modified: August 09, 2007
E-mail: OFM.Forecasting@ofm.wa.gov