Concept: Estimated daytime population* equals the total population, plus the in-commuters, minus the out-commuters.
Method 1 (intuitively easy to follow, but requires getting the number of workers who lived and worked in same county/place, and then calculating incommuters and outcommuters)
| Total resident population | + | Incommuters (total workers working in area/place minus workers who lived and worked in same county/place) |
- | Outcommuters (total workers living in area/place minus workers who lived and worked in same county/place) | = | Estimated daytime population | Area name |
| 43,671 | + | 3,748 | - | 11,937 | = | 35,482 | Autauga County, AL |
Method 2 (alternative that is simpler to calculate and requires fewer, more readily available data items)
| Total resident population1/ | + | Total workers working in the area or place2/ | - | Total workers living in the area or place3/ | = | Estimated daytime population | Area name |
| 43,671 | + | 11,619 | - | 19,808 | = | 35,482 | Autauga County, AL |
Algebra: (why method 2 produces the same result as method 1)
| daytime pop | = | total pop + incommuters - outcommuters | ||||||
| = | total pop + (total workers working in area/place - workers who lived and worked in same county/place) - outcommuters | substitute (incommuters = total workers working in area/place - workers who lived and worked in same county/place) | ||||||
| = | total pop + (total workers working in area/place - workers who lived and worked in same county/place) - (total workers living in area/place - workers who lived and worked in same county/place) | substitute (outcommuters = total workers living in area/place - workers who lived and worked in same county/place) | ||||||
| = | total pop + (total workers working in area/place - |
cancel | ||||||
| = | total pop + total workers working in area/place - total workers living in area/place | reduce | ||||||
Data Sources:
1/ Census 2000 Summary File 3 (SF3), Table P3. Note that this is based on the 100-percent population count and may differ from the total population in Table P1, which is based on sample data. Click on "Data Sets" at factfinder.census.gov.
2/ Census Transportation Planning Package 2000, Part 2 -Data by place of work. The "Total" from any table with a universe of "All workers" will give the total working in the area. Click on CTPP 2000 at www.fhwa.dot.gov/ctpp/ to download data for a particular summary level and state from Part 2.
3/ Census 2000 Summary File 3 (SF3), Table P30. The "Total" line gives the number of resident workers, or workers living in the area. Click on "Data Sets" at factfinder.census.gov
Contact: Journey to Work and Migration Statistics Branch, Population Division, US Census Bureau, (301) 763-2454.
* The Census Bureau estimate of daytime population adjusts only for work-related travel, i.e., incommuters to an area and outcommuters from an area. Data necessary to adjust for shopping, school, recreation, tourism, etc. are not available.
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