You state registration is meaningless in DC: 95% of the vote is for the democrats in that city and the city is less than 50% black. In NYC, the dems take 80% or more of the vote, so in these two cities, registration by party is significantly meaningful.
I am referring to national party registration numbers like those announced in the article. Those are meaningless, voter registration laws vary by state. There are at least 20 states without party registration. Those states are largely in the south and Midwest.
So any national numbers of voters party registration really only represent about half of the country, and a disproportionately Democrat half at that.