Processing errors were discovered in the 2009 ACS 1-Year Summary File that was released on September 28, 2010. The errors affected fifteen sequences: 1, 2, 107, 108, 113, 114, 164, and 169-176. These errors occurred in both the estimate (e) and margin of error (m) files.

Sequences 164, 169, 170, and 176 were replaced for Puerto Rico only. The other erroneous sequences were replaced for most or all areas.

The corrected sequences were released on January 26, 2011.