By Dave Shiflett Sept. 27, 2018 5:49 p.m. ET Given the choice between hearing a country-music crooner or a cat in a blender, many Americans might give us reason to fear for the fate of the cat. Others consider country the music that red-state deplorables listen to, even if it’s hardly restricted to hayseeds, malevolent or otherwise. Even Beyoncé sings a little country. Beyoncé is a little late to the hayride, as we are reminded by the 50th-anniversary edition of Bill C. Malone’s “Country Music USA.” Mr. Malone, a musician and a professor emeritus at Tulane, traces country’s origins to songs brought over by colonials—the fiddler Thomas Jefferson described an instrument called the “banjar” in 1781—and follows the music through its many variations and mutations to the present day. Country music, Mr. Malone writes, is a “vigorous hybrid” based on a foundation mostly Southern, rural, Protestant and working class. Early audiences flocked to tent repertory or “Toby” shows, where the price of admission (often paid with eggs and other rural currency) bought an afternoon of music and other distractions, including magic shows and trained bears. Two later advances greatly expanded the music’s reach. During a seven-year stretch in the 1920s, Mr. Malone notes, annual radio sales jumped more than 10-fold, while some estimates reported a radio in every third home, more than a few dialed into country stations. The other boost to country came from Ralph Peer (1892-1960), an energetic Missouri native who “first presented country music to the American public.” Peer didn’t pick, but his efforts as a talent scout, recording engineer and pioneering music publisher surely made him grin—and fairly rich. Mr. Malone, who seems to have profiled everyone ever associated with country music, questions the “authenticity” of some latter-day artists. Country, he writes, “has been inundated by musicians whose sounds suggest neither regional, rustic nor blue-collar nativity, but are instead rooted in the homogenizing and mass-consumption-oriented media establishment.” For this anniversary edition, he brings in scholar Tracey E.W. Laird to add a final chapter addressing modern country’s “meaning, identity and relationship with its multiple audiences.” Ms. Laird sings a more academic tune than Mr. Malone, at one point explaining that branding—as crucial for country stars as it is for cars and candy bars—“operates according to multidimensional relationships of signs and meanings, not corresponding object to object, but with shifting points of connection, nearly always in flux.” That observation may leave many banjo players scratching their heads, but she has a “big tent” approach and is as comfortable with the Dixie Chicks and Beyoncé—whose twang-inspired efforts rankle purists—as with Hank Williams. Jocelyn R. Neal ponders some of the same questions in “Country Music: A Cultural and Stylistic History,” a textbook that covers much of the same biographical ground that Mr. Malone does (though not in as much detail), augmented with a wagonload of analysis. Some fans might find the interpretations a bit thick, especially a series of “listening guides” that deconstruct classic songs. The opening line to “Rocky Top” (“Wish that I was on old Rocky Top”) is said to describe “an anti-modernist nostalgia,” while the appearance of “two strangers” in a later verse presents “cultural stereotypes that will become part of bluegrass’ reputation”—i.e., “backwoods people who are closed to outsiders, who live beyond the reach of both law and civilization.” Yet Ms. Neal illuminates other points in perfect pitch. In a discussion of the country bona fides of hit-maker Shania Twain, Ms. Neal quotes a critic who called her the “highest-paid lap dancer in Nashville”—not only offering deep insight but also reminding us that country music has come a long way since Jefferson’s “banjar.” —Mr. Shiflett posts his original music and journalism at www.Daveshiflett.com.