I think the best bet for preserving white demographic majority is in Nebraska, Iowa, Kansas, Missouri, Wyoming, West Virginia, West Penn, and then the far Northeast Region. Kansas's southwest corner percentages don't look good, but upon further investigation, many of those counties have a population below 1,000... not beyond saving, even 50 white families moving to those counties changes them from below 40% white to 90% white. Kansas, Missouri, and Nebraska actually had several counties that saw an INCREASE in white population, as well as West Virginia.
The worst offenders, the states who saw a significant decrease in its white population, was Texas, Virginia, New Mexico, Arizona, parts of California, and Mississippi.