Census Tabulation Block (TABBLOCK)
Overview
Census Tabulation Block (TABBLOCK) is the smallest geographic unit used by the U.S. Census Bureau for data collection and tabulation, typically bounded by visible features such as roads or rivers. There are approximately 8 million census blocks in the United States.
Key Concepts
Visible features are physical boundaries like streets, roads, railroads, streams that define block edges. Non-visible features are legal boundaries (city limits, county lines) that may also define blocks. Block number is a 4-digit code within a census tract, where the first digit indicates the block group. GEOID combines state (2) + county (3) + tract (6) + block (4) = 15 digits. Zero population blocks include water, parks, commercial areas with no residents.
Data Availability
| Data Type | Available at Block Level |
|---|---|
| Population counts | Yes (decennial census) |
| Housing unit counts | Yes (decennial census) |
| Demographics (age, race) | Yes (decennial census) |
| ACS estimates | No (block group minimum) |
| Economic data | No |
Appendix
Created: 2025-12-13 | Modified: 2025-12-13
See Also
- Block Group (BG)
- Topologically Integrated Geographic Encoding and Referencing (TIGER)
- Federal Information Processing Standards (FIPS)