I want to know more about minority-majority districts. How many of them are there, and what percentage of minority-majority districts are represented by Democrats in the House of Representatives?
According to wikipedia:
There are 23 districts with a majority African American electorate, and 1 with a majority Asian American electorate.
All 24 are represented by members of the Democratic Party, and all except Rep Steve Cohen (TN-9) identify as Black or Asian.
There are also 20-odd districts with a majority Hispanic (any race).
(Note that the wikipedia list is somewhat out of date)
Using the latest available (2018) data from the American Community Survey, we can obtain a list of congressional districts with a minority-majority population - that is to say, districts where the proportion of the population identifying as 'White Alone' is less than 50%.
Of the 435 congressional districts, as well as Puerto Rico & D.C.'s non-voting delegates, 58 have a minority-majority population. All 58 are represented in the 116th Congress by Democratic representatives, except for Georgia's 5th Congressional District, which is currently vacant following Democratic Rep. John Lewis' death in July 2020.
Below is a map showing the location of these 58 districts, categorized by the largest racial demographic within the district.
Below is the full list of minority-majority districts for the 116th Congress:
Congressional District,Pop.,White Alone Pop.,Percent White Alone NY-15,743959,128998,17.34 HI-1,709286,122457,17.26 NY-5,757972,132518,17.48 NY-13,795633,203890,25.63 TN-9,712723,188242,26.41 GA-4,785104,210961,26.87 MD-4,760398,211823,27.86 CA-17,777468,222919,28.67 NJ-10,759704,218853,28.81 GA-13,757521,220074,29.05 NY-8,791211,246189,31.12 LA-2,794121,247841,31.21 MS-2,695797,218531,31.41 HI-2,711205,223195,31.38 GA-5,793039,251276,31.69 PA-3,736340,242730,32.96 AL-7,660468,221541,33.54 TX-9,786925,265656,33.76 CA-34,748812,259995,34.72 MI-14,704494,244398,34.69 MD-7,716136,251762,35.16 NY-9,730957,262344,35.89 FL-20,809153,295544,36.53 IL-2,694459,253856,36.55 IL-7,707513,264669,37.41 CA-27,705509,266686,37.80 SC-6,659483,256307,38.86 MI-13,663867,260452,39.23 OH-11,678001,269493,39.75 CA-15,789174,314637,39.87 CA-38,716331,292100,40.78 CA-43,753696,307860,40.85 CA-13,764304,312333,40.87 DC-1,702455,296747,42.24 NY-14,706440,298774,42.29 GA-2,665539,281955,42.36 NY-6,734183,313127,42.65 FL-24,784469,337035,42.96 IL-1,706550,303613,42.97 CA-14,759415,328620,43.27 MO-1,728365,315884,43.37 CA-19,763028,334224,43.80 CA-44,725177,320876,44.25 VA-3,744804,330195,44.33 CA-35,769589,341427,44.36 FL-5,738862,331585,44.88 NY-16,732981,334077,45.58 PA-2,727380,333199,45.81 NC-12,880550,405087,46.00 MD-5,757621,358663,47.34 NC-1,761087,363018,47.70 CA-12,764043,365047,47.78 WA-9,765285,367222,47.98 CA-37,738174,355343,48.14 TX-18,801885,388019,48.39 WI-4,710573,351094,49.41 NV-1,685427,339750,49.57 CA-6,777985,386232,49.65