I have no doubt the data for this map is scrupulously accurate, but the method of display is very misleading.

True, the majority of the population of this country can be classified in the "white" ethnic group, but a glance at this map would suggest that they were the overwhelming majority, when they are not.

However, the predominance of whites in rural and low-population areas, and the heavy concentration of ethnics in urban areas, gives a misleading picture when mapped this way. It makes it look like the country is mostly white, with a few isolated pockets here and there of non-whites. This is not exactly the case, and the misperception is not a flaw of the data, but a shortcoming of the display method. The blue dots are easiest seen out in the tules, but most Americans (82%) live in the cities where the dots merge.

The key figures to keep in mind (from the 2010 census):

Non-Hispanic white and European - 63.7%
Non-Hispanic black - 12.2%
Hispanic - 16.4%
Asian - 4.8%
Native American - 0.9%

http://en.wikipedia.org/wiki/Demographics_of_the_United_States#Race_and_ethnicity