Finally, the ranking was done by combining percentage of black population in first place and LGBT population percentage figures that we have provided. However, the percentage of the black gay population could not be obtained with certainty, so we have ranked cities by percentage of the LGBT population in general but taking in mind only the “black cities” we have explained above. So, our search idea for this list was similar to one we have done for 15 Gayest Cities in America Per Capita in 2018, which was mostly based on researches done by Gallup. So, on this broader picture, you might be interested in going through the 10 Gayest Countries in Europe.
Speaking about a wider demographic framework, it is somewhat easier to get more precise figures for the LGBT population for countries rather than cities (though you can check out what the results were for the 15 Gayest Cities in the World).