Sources & Methodology
Data Sources
- American Community Survey (ACS) 5-Year Estimates (2000–2023): Core source for county- and state-level data on population, race and ethnicity, income, poverty, education, housing, commuting, language, nativity, veterans, and more.
- ACS 1-Year Estimates: Used selectively for state-level trends where annual data are available and reliable.
- Decennial Census (2000, 2010, 2020): Used for baseline comparisons in long-term population, race/ethnicity, and housing trends.
- Historical State Population Tables (1800–1990): Used for long-range population growth context.
Variable Documentation
The specific ACS tables or variables used are noted on each individual map or chart page. To explore ACS variables directly, visit the Census Bureau’s Data API Variable Finder.
Data Access and Tools
- Data accessed primarily through the
tidycensuspackage in R, which interfaces with the U.S. Census Bureau API. - Data wrangling performed with
dplyr,tidyr, andpurrr. - Geographic data (state, county, tract shapes) handled with
sfandtigris, including adjustments for Alaska, Hawaii, and D.C. - Maps rendered with
leaflet(interactive) and exported as static HTML usinghtmlwidgets. - Charts generated with
ggplot2,plotly, andChart.jsfor interactive visualizations.
Map and Visualization Notes
- Color scales created with
RColorBrewerpalettes, adjusted for readability and consistency across topics. - Legends standardized with percent or ratio formatting for easier interpretation.
- State-level pages often include unique breakdowns, such as mirrored income pyramids, nativity-based race charts, and age-gender population pyramids.
Attribution
- All data provided by the U.S. Census Bureau. While public, data were processed, combined, and visualized independently by SSDAN.
- Visualizations, cleaning steps, and site integration are original work by SSDAN interns and staff using open-source tools.
Contact
Questions about data sources or technical methods can be directed to SSDAN at ssdan@umich.edu.