One of the many bad results of a voluntary (instead of the current mandatory) American Community Survey (ACS) would be no useable data on over 40 percent of U.S. counties. Here is a helpful map of the counties (in purple) that, in the best case scenario, would still produce no useable data from a voluntary ACS.

This is one of many reasons that MRA opposes Congressman Poe's amendment and similar measures to make the ACS voluntary.

(You can also download a pdf of this map).