The various genres of American vernacular music were, at the time of their inception, heavily associated with specific racial and ethnic groups. Bebop began as a black cultural statement, and some of its originators deliberately tried to exclude white musicians and listeners. Country music, meanwhile, was the province of white Westerners and Southerners; blacks were not invited to participate.

Perhaps it’s a sign of how far we’ve come that a growing number of our finest black jazz vocalists regularly sing country songs, while some of the most accomplished singers of contemporary bebop and blues are white. Two new albums, Cassandra Wilson’s “Thunderbird” (Blue Note) and Catherine Russell’s “Cat” (World Village), find black jazz singers dabbling in country, while a third, Karrin Allyson’s “Footprints” (Concord), features a white woman showing off her bebop chops.

Ms. Wilson is the slowest singer in contemporary jazz. Her characteristic sound, closely informed by the late Nina Simone, is an even monotone delivered at a crawl. She doesn’t emphasize key points in a lyric by singing certain words faster or louder than others; rather, through refined vocal witchcraft, she can get you to listen harder whenever she wants to.

Her main strength, though, is the way she interprets a diverse range of material in intriguingly open, generally acoustic spaces. Unfortunately, she has chosen on “Thunderbird” to interpret a much narrower range of material, in more electronic settings. These backgrounds, which seem to use a lot of sampling and other artificial effects, are dense and busy and not particularly attractive to my ears. The original songs, most of them by Ms. Wilson and her producer, T-Bone Burnett, are, for the most part, entirely forgettable.

Compared with 2003’s “Belly of the Sun,” which may be her finest hour, “Thunderbird” is a disappointment. But the new album has a handful of highly enjoyable songs – none of them among the newly written material.

On “Closer to You,” a tune by Jakob Dylan of the rock band the Wallflowers, Ms. Wilson’s voice relates agreeably to the electronic background and the source material. On “I Want To Be Loved” by Willie Dixon, the composerlaureate of the Mississippi-to-Chicago blues experience, Ms. Wilson gets into a groove as erotic as any I have heard from her.

“Easy Rider” is Ms. Wilson’s treatment of a traditional blues line that jazzmen in New Orleans and the South have been playing and singing for more than a century. She starts small, accompanied only by bass and guitar in a quiet dynamic, and gradually builds up tension over seven minutes of variations on an archetypical 12-bar phrase, until, as she sings, “the tears come rollin’ down.”

But the highlight of “Thunderbird” is “Red River Valley,” a 19th-century song that actually originated in upstate New York (as “The Bright Mohawk Valley”) before migrating west and becoming one of the best known of all traditional cowboy songs. Following a gently weeping guitar intro, Ms. Wilson sings it mostly a capella, and the wide-open spaces of her music paint pictures of the prairie in the listener’s brain. She might have been tempted to follow the typical trajectory of small and quiet to big and loud, but she doesn’t, holding the stage with characteristically understated emotion throughout.

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Like Ms. Wilson, Ms. Russell is among the few jazz-based singers who consistently perform old-time country songs. But her delivery is much more upbeat, sunny, and animated.

Ms. Russell’s debut album is a collection of diverse songs from a surprising variety of pop, jazz, and blues sources, rendered in an acoustic setting that often seems more like country than jazz. Ms. Russell deftly manages to combine an older string-band sound (featuring, at different points, mandolin, banjo, accordion, and fiddle) with a grinding jazz beat.

The daughter of two important jazz musicians – the pioneering female bassist Carline Ray and the New Orleans-born pianist and bandleader Luis Russell, one-time musical director of Louis Armstrong’s orchestra – Ms. Russell has been working around New York for many years. But she didn’t come to the attention of the larger jazz world until her performance in the Doc Cheatham centennial celebration at last year’s JVC Jazz Festival.

Her father’s most famous composition is the Armstrong specialty “Back O’ Town Blues,” which, as Ms. Russell announced from the stage at Joe’s Pub during her CD release show last month, paid for the Armstrong family’s new Cadillac in 1956. Appropriately, “Back O’ Town Blues” is one of the highlights of Ms. Russell’s new album.

The song follows the classic 12-bar form structurally, but is unusual lyrically in that each section features a different second line rather than repeating the first, as is customary. She also sings in an R&B style that is much more aggressive than Armstrong’s relaxed, comic version.

Ms. Russell keeps the groove going no matter her inspiration. Dinah Washington’s hit “My Man’s an Undertaker” is rendered with a heavy two-bit beat out of the Bessie Smith era; she takes Louis Jordan’s R&B hit “Juneteenth Jamboree” and merges it with the King Oliver-associated jazz standard “Royal Garden Blues.”Showing her love for Patsy Cline, Ms. Russell reprises one of the Nashville diva’s hits, “Someday You’ll Want Me To Want You.” She has also written a new song in the Cline style, “Blue Memories,” and includes a number of jazz and pop standards, most notably two dreamy songs by James Van Heusen, “Deep in a Dream” and “Darn That Dream.”

Throughout, Ms. Russell is more than just the sum of her inspirations and influences: She is a fresh and original voice. “Cat” is the most exciting debut album I’ve heard in a long time.

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Ms. Allyson, who had a brief dalliance with 1970s-style singer-songwriter material on her previous album, has returned to what she does best with “Footprints.” This ambitious project celebrates the tradition of attaching words to classic jazz tunes, and in the process honors the two greatest writers in that genre, Jon Hendricks – who contributed both his words and his voice to the album – and the late Oscar Brown Jr. Apart from two songs by Brown, the set consists of new texts to bebop standards like “Jordu” and “Con Alma,”most of which are by pianist and poet Chris Caswell.

Ms. Allyson’s only wrong turn is in Brown’s “But I Was Cool,” a piece that was too specific to the late songwriter – and too comically self-deprecating for such an attractive and poised woman – to put over convincingly. But she’s winningly funky on Hank Mobley’s “The Turnaround,” supported by musical director Bruce Barth on electric piano, which takes us twisting through the short-lived era of the jazz boogaloo.

It took nerve to make Wayne Shorter’s “Footprints” the focal point of the album, since several sets of lyricists and singers have already had a hack at this jazz standard. But Mr. Caswell’s set of words to Mr. Shorter’s melody are the first that actually add something to my enjoyment of it. Throughout, Ms. Allyson enhances the jazz tradition rather than merely riding on its coattails.

wfriedwald@nysun.com