Amanda Shires, Brandi Carlile, Maren Morris, Natalie Hemby - Carlile's the only one of this country supergroup (see also: Pistol Annies - who are good but the Highwomen are better) who I really know, and even then only from earlier in her career, but that doesn't matter because the quality on display speaks for itself.
There's soul here, right from the get go with "Highwomen" the song, along with mid-tempo melody ("Redesigning Women", "Crowded Table"), a good line in ballads when they want to ("My Only Child") and a repertoire of enjoyable upbeat variations on country, roots and Americana styles among which the blues/rockabilly "Don't Call Me" is my favourite. And it's an explicitly feminist project too, beyond even the simple fact of these four highly capable women coming together in a vein and genre traditionally dominated by men.