Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

Bridged-Race 1990-1999
Intercensal Population Estimates
for Calculating Vital Rates
(with Single Year of Age Detail)

On July 26, 2004, the National Center for Health Statistics released bridged-race intercensal estimates of the resident population of the United States for 1990-1999 with single year of age detail at the county, state and national levels.

Note that in this release, the county, state and national level population totals are not consistent for for the years 1991-1999. The national level estimates in this release are consistent with the estimates in the April 15, 2003 release of the Bridged-Race 1990-1999 Intercensal Population Estimates with Selected Age Groups.

These bridged intercensal population files contain estimates of the resident population of the United States as of July 1, 1990 - July 1, 1999 by single-year of age (0, 1, 2, ..., 85 years and over), bridged-race category (White, Black or African American, American Indian or Alaska Native, Asian or Pacific Islander), Hispanic origin (not Hispanic or Latino, Hispanic or Latino), and sex (1). The original data files consist of 4 county-level files, one state-level file, and one national-level file. The estimates in the intercensal files are based on both the 1990 census and the 2000 census with bridged-race categories (3) and are a revision of the annual time series of July 1 county population estimates by age, race, sex, and Hispanic origin (the postcensal estimates). The intercensal files were produced by the Population Estimates Program of the U.S. Census Bureau with support from the National Cancer Institute and in collaboration with the National Center for Health Statistics (NCHS). The 4 county-level files, state-level file, and national-level file released on July 26 2004 replace the 4 county-level single-year of age intercensal files that were released by NCHS on April 30, 2004.

The county-level files released on April 30 2004 have been replaced because they were found to have cells with a population count of ngative one ("-1") due to rounding. As it was not feasible to rake the file to remove the negative one values, the solution was to convert the negative one values to zeros. Conversion of the "-1"s to zeroes increases subtotals and totals. To minimize the impact of the conversion on subtotals and totals, state-level and national-level files were created, in addition to the county-level file. The county-level, state-level, and national-level files were created from the original county-level file (with the -1 population counts) as follows:

  1. The revised county-level file (in 4 parts) was created by converting all -1s (n=423) to zero.
  2. The state-level file was created by aggregating the original county-level file (with the -1s) to the state-level. Any -1s remaining after aggregation were converted to zero (n=72).
  3. The national-level file was created by aggregating the original county-level file (with the -1s) to the national level. No -1s remained after aggregation.

Number of -1s converted to zero in the county and state files, by year:


		Number of -1s converted to zero
Year		State file	County file
1990		     0			 0
1991		     1			 1
1992		     7			18
1993		     8			30
1994		     5			40
1995		    10			75
1996		     7			49
1997		     7			70
1998		    12 			64
1999		    13			70
All years	    72		       423

Note:

Subtotals and totals obtained from the resulting county-level files will not be consistent with those obtained from the state-level and national-level files. Further, subtotals and totals obtained from the state-level file will not be consistent with corresponding subtotals and totals from the national-level file. Thus, it is recommended that the county-level file not be used to calculate state and national vital rates and that the state-level file not be used to calculate national vital rates. All subtotals and totals from the single-year of age national-level file are consistent with those from the previously released (April 15, 2003) 5-year age group county-level files (2).

Background

Derivation of the race-specific intercensal population estimates for the 1990's was complicated by the incomparability of the race data on the 1990 and 2000 censuses. The race data on the 1990 census were collected in accordance with the Office of Management and Budget's (OMB) 1977 standards on race and ethnicity, while the race data on the 2000 census were collected in accordance with the OMB's 1997 standards on race and ethnicity (4,5).

In 1997, OMB issued "Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity," which supersedes the 1977 Statistical Policy Directive 15, "Race and Ethnic Standards for Federal Statistics and Administrative Reporting" (4,5). Both documents specify rules for the collection, tabulation, and presentation of race and ethnicity data within the Federal statistical system. The 1977 standards required Federal agencies to report race-specific tabulations using four single-race categories, namely, White, Black, American Indian or Alaska Native, and Asian or Pacific Islander. The 1997 revision incorporated two major changes designed to reflect the changing racial and ethnic profile of the United States. First, the 1997 revision increased from four to five the minimum set of categories to be used by Federal agencies for identification of race. As in the past, these categories represent a social-political construct and are not anthropologically or biologically based. The five categories for race specified in the 1997 standards are: American Indian or Alaska Native; Asian; Black or African American; Native Hawaiian or Other Pacific Islander; and White. Second, the revised standards add the requirement that Federal data collection programs allow respondents to select one or more race categories when responding to a query on their racial identity. This provision means that there are potentially 31 race groups, depending on whether an individual selects one, two, three, four, or all five of the race categories. Collection of additional detail on race or ethnicity is permitted so long as the additional categories can be aggregated into the minimum categories. During the transition to full implementation of the 1997 standards, two different standards for the collection of race and ethnicity data are being used, creating incomparability across data systems. Further, within a given data system, the change in the race standards results in incomparability across time, thus making it difficult to perform trend analyses. The OMB recognized that approaches to make data collected under the 1997 standards comparable to data collected under the 1977 standards would be needed. Therefore, the OMB issued "Provisional Guidance on the Implementation of the 1997 Standards for Federal Data on Race and Ethnicity" (6). The guidance document contains a detailed discussion of bridging methods.

Vital rates are based on information obtained from vital records collected through the state-based Vital Statistics Cooperative Program (numerators) and population estimates based on the U.S. Census (denominators). The 2000 decennial census collected race and ethnicity data in accordance with the 1997 standards. However, full implementation of the 1997 standards within the Vital Statistics Cooperative System had not occurred at that time. Indeed, for this data system, implementation of the 1997 standards is being phased in over several years as the States revise their birth and death certificates to reflect the 1997 standards. Thus, beginning with the 2000 data year, the numerators and denominators for vital rates have incompatible race data. While 1990-based postcensal estimates of the July 1, 2000 and July 1, 2001 resident population were used as denominators in the calculation of vital rates for 2000 and 2001, it was necessary to develop a bridging method so that race-specific intercensal population estimates and postcensal population estimates based on Census 2000 could be developed for use in calculating vital rates.

The bridging methodology developed by NCHS bridges the multiple-race group population counts to single-race categories. Information from the pooled 1997-2000 National Health Interview Survey was used to develop the bridging methodology. Regression models with person-level and county-level covariates were used to generate the probability of selecting each single-race category possible for a multiple-race group. The probabilities generated from the fitted regression models are referred to as the NHIS bridging proportions. The Census Bureau applied the NHIS bridging proportions generated by NCHS to the Census 2000 Modified Race Data Summary file (7). This application resulted in a bridged population count for each of the four single-race categories (White, Black or African American, American Indian or Alaska Native, and Asian or Pacific Islander) by county, single-year of age, Hispanic origin group, and sex, for April 1, 2000. The bridging methodology is described in detail in the report, "a href="populations/bridged-race/VitalHealthStatistics-Series2No135.pdf">United States Census 2000 Population with Bridged Race Categories and in a related report (8,92).

The race classification used for the bridged-race intercensal estimates is consistent with the four single-race categories enumerated in the 1990 Census (White; Black; American Indian or Alaska Native, and Asian or Pacific Islander). To produce the race-specific intercensal estimates the Census Bureau used the same methodology that was used to produce the age-sex-specific national and state intercensal estimates to distribute the difference between the 1990-based postcensal estimates of the 2000 resident population and the bridged-race April 1, 2000 population estimates (6).

Release of estimates

In response to the need for bridged estimates by a wide range of users, NCHS is making the bridged-race population estimates available for download from http://www.cdc.gov/nchs/about/major/dvs/popbridge/popbridge.htm.

Although efforts were made to use the best available data and methods to produce these estimates, the modeling process introduces error into the estimates. The potential for error will be greatest for the smallest population groups, particularly the smaller race groups and county-level estimates. The bridged estimates may be updated as additional data become available for use in the bridging process.

NCHS would appreciate receiving feedback on the usefulness of the estimates as well as notification of any problems that have been identified. Please provide comments via e-mail to: PopEst@cdc.gov.

Suggested citation:

National Center for Health Statistics. Bridged-race intercensal estimates of the July 1, 1990-July 1, 1999, United States resident population by county, single-year of age, sex, race, and Hispanic origin, prepared by the U.S. Census Bureau with support from the National Cancer Institute. Available on the Internet at: http://www.cdc.gov/nchs/about/major/dvs/popbridge/popbridge.htm. July 26, 2004.

References

1. National Center for Health Statistics. Bridged-race intercensal estimates of the July 1, 1990-July 1, 1999, United States resident population by county, single-year of age, sex, race, and Hispanic origin, prepared by the U.S. Census Bureau with support from the National Cancer Institute. Available on the Internet at: http://www.cdc.gov/nchs/about/major/dvs/popbridge/popbridge.htm, April 24, 2004.

2. National Center for Health Statistics. Bridged-race intercensal estimates of the July 1, 1990-July 1, 1999, United States resident population by county, age group, sex, race, and Hispanic origin, prepared by the U.S. Census Bureau with support from the National Cancer Institute. Available on the Internet at: http://www.cdc.gov/nchs/about/major/dvs/popbridge/popbridge.htm, August 1, 2003.

3. National Center for Health Statistics. Estimates of the April 1, 2000, United States resident population by county, age group, sex, race, and Hispanic origin, prepared under a collaborative arrangement with the U.S. Census Bureau. Available on the Internet at: http://www.cdc.gov/nchs/about/major/dvs/popbridge/popbridge.htm, January 8, 2003.

4. Office of Management and Budget. Revisions to the standards for the classification of Federal data on race and ethnicity, Federal Register 62FR58781-58790, October 30, 1997. Available on the Internet at: http://www.whitehouse.gov/omb/fedreg/1997standards.html, and here.

5. Office of Management and Budget. Race and ethnic standards for Federal statistics and administrative reporting. Statistical Policy Directive 15, 1977. Available on the Internet as "Appendix A" at: http://www.census.gov/population/www/socdemo/race/Directive_15.html, and here.

6. Office of Management and Budget. Provisional guidance on the implementation of the 1997 standards for the collection of Federal data on race and ethnicity. December 15, 2000. Available on the Internet at: http://www.Whitehouse.gov/omb/inforeg/r&e_guidance2000update.pdf and here.

7. U.S. Census Bureau. Census 2000 Modified Race Data [MR(31)-CO.txt], prepared by the U.S. Census Bureau, 2002. Available on the internet at http://www.census.gov/popest/estimates.php, and here.

8. Ingram DD, Weed JA, Parker,JD, Hamilton B, Schenker N, Arias E, Madans JH. United States Census 2000 population with bridged race categories. Vital Health Stat 2(135). Hyattsville, Maryland: National Center for Health Statistics. 2003.

9. ParkerJD, Schenker N, Ingram DD, Weed JA, Heck KE, Madans JH. Bridging between two standards for collecting information on race and ethnicity: application to Census 2000 and vital rates. Public Health Reports 119 (2), p. 192-205. 2004. Available on the Internet at: http://www.publichealthreports.org/userfiles/119_2/119192.pdf, and also here.

10. Bureau of the Census. Methodology: national intercensal population estimates. 2002. Available on the Internet at: http://www.census.gov/popest/topics/methodology/, and also here.

File layout for the Bridged Intercensal Files, 1990-1999, With Single-year of Age Detail

The single-year of age intercensal population estimates are being released on county-level, state-level, and national-level files. To facilitate downloading, the county-level single-year intercensal file has been divided into four parts:

Part 1 has population estimates for 1990-99 for Alabama-Indiana.
Part 2 has estimates for Iowa-Missouri;
Part 3 has estimates for Montana-South Carolina, and
Part 4 has estimates for South Dakota-Wyoming. Each of the files contains bridged-race intercensal estimates of the resident population of the United States as of July 1, 1990-July 1, 1999 by single-year of age (0, 1, 2, ..., 85 years and over), bridged-race category (White, Black or African American, American Indian or Alaska Native, Asian or Pacific Islander), Hispanic origin (not Hispanic or Latino, Hispanic or Latino), and sex. The population estimates on these files were derived using the bridged April 1, 2000 resident population file (3). These files were released by NCHS on July 26, 2004. They replace a county-level single-year of age intercensal file previously released by NCHS on April 30, 2004.

Note that in this release, the county, state and national level population totals are not consistent for for the years 1991-1999. The national level estimates in this release are consistent with the estimates in the April 15, 2003 release of the Bridged-Race 1990-1999 Intercensal Population Estimates with Selected Age Groups.


File release date: 	July 26, 2004

File name:		Description:		Number of records:

icen_natA1.txt		National file		    1,376	

icen_stA1.txt		State file		   70,176

			County Files	

icenA1_1.txt		Alabama-Indiana		1,081,536
icenA1_2.txt		Iowa-Missouri		1,113,184
icenA1_3.txt		Montana-South Carolina	1,051,264
icenA1_4.txt		South Dakota-Wyoming	1,076,032


							Control totals
Year	Description			National file	  State file	County file
1990	July 1, 1990 population  	249,622,814	  249,622,814	249,622,814				
1991	July 1, 1991 population 	252,980,941	  252,980,942	252,980,942			
1992	July 1, 1992 population 	256,514,224       256,514,231   256,514,242
1993	July 1, 1993 population 	259,918,588       259,918,595   259,918,618
1994	July 1, 1994 population 	263,125,821       263,125,826	263,125,867
1995	July 1, 1995 population 	266,278,393	  266,278,403	266,278,468
1996	July 1, 1996 population 	269,394,284	  269,394,291	269,394,333
1997	July 1, 1997 population 	272,646,925	  272,646,932	272,646,995
1998	July 1, 1998 population 	275,854,104	  275,854,116	275,854,168			
1999	July 1, 1999 population 	279,040,168	  279,040,181	279,040,238


				File Layout 
Field 
Location  Size	Code Outline					Format

1-2	   2	FIPS State code					Numeric
			00=national file

3-5	   3	FIPS county code			   	Numeric
		000=state and national files

6-7	   2	Age						Numeric
		(0, 1, 2, ..., 85 years and over)

8	   1	Race-sex					Numeric
		1=White male
		2=White female
		3=Black or African American male
		4=Black or African American female
		5=American Indian or Alaska Native male
		6=American Indian or Alaska Native female
		7=Asian or Pacific Islander male
		8=Asian or Pacific Islander female

9	   1 	Hispanic origin					Numeric
		1=not Hispanic or Latino
		2=Hispanic or Latino

10-17	   8	Population estimate for July 1, 1990		Numeric
18-25      8	Population estimate for July 1, 1991		Numeric
26-33	   8	Population estimate for July 1, 1992		Numeric
34-41	   8	Population estimate for July 1, 1993		Numeric
42-49	   8	Population estimate for July 1, 1994		Numeric
50-57	   8	Population estimate for July 1, 1995		Numeric
58-65	   8	Population estimate for July 1, 1996		Numeric
66-73	   8	Population estimate for July 1, 1997		Numeric
74-81	   8	Population estimate for July 1, 1998		Numeric
82-89	   8	Population estimate for July 1, 1999		Numeric

Source:

Documentation for single-year-of-age detail bridged-race intercensal population estimates for July 1, 1990-July 1, 1999 (5-year age groups), which was released on July 26, 2004 is on the internet at ftp://ftp.cdc.gov/pub/Health_Statistics/NCHS/datasets/nvss/bridgepop/DocumentationBridgedIntercenA1.doc.




This page last reviewed: Tuesday, January 05, 2016
This information is provided as technical reference material. Please contact us at cwus@cdc.gov to request a simple text version of this document.
TOP