“Pioneers of Television” (7 p.m., PBS, check local listings) looks back at classic Westerns. For a time in the late 1950s, the sturdy genre did not so much dominate the television schedule as devour it entirely.

The perennial third-place network ABC devoted many half-hours to shows like “Colt .45,” “Maverick,” “Lawman” and “Cheyenne.” Over on NBC, you would see “Riverboat,” “Tales of Wells Fargo,” “Wagon Train,” “Wichita Town,” “Law of the Plainsman,” “Bat Masterson” and its new show “Bonanza.” CBS offered “The Texan,” “Johnny Ringo,” “Dick Powell’s Zane Grey Theatre,” “Rawhide,” “Wanted Dead or Alive,” “Have Gun, Will Travel” and “Gunsmoke,” the longest-running Western of them all. And those are just shows from the 1959 season.

People couldn’t get enough of the cowboy shoot’em-ups and for a very interesting reason.

Throughout most of its first decade, television was starved of Hollywood product. Many studio chiefs (Walt Disney was a notable exception) treated the medium as a fad and kept many movies off television and refused to allow their studios to produce material for broadcast. As a result, many of the acclaimed dramas of TV’s “Golden Age” were produced in New York and starred Broadway actors. Gritty dramas like “Marty,” “Twelve Angry Men” and “Days of Wine and Roses” originated on television and only later became award-winning films.

Round about the late 1950s, Hollywood seemed to admit that TV was here to stay. The studios began to churn out half-hour television Westerns with the same efficiency that they had produced B-movies.

Given the choice between watching a “serious” actor delivering angst-ridden dialogue in a stagy New York production and watching a young Clint Eastwood or James Garner dispatching bad guys with six-shooters, the average viewer chose the cowboys in a landslide.

Westerns arrived en masse and all but ended “serious” network television and remained a programming staple until “Gunsmoke” was canceled in 1975. Elements of the Western would show up in outer-space dramas, the gangster genre and even “24,” but the hugely popular classic TV Western remains as dead as vaudeville.

• Fans who think they know all about Joan Rivers from her recent documentary “A Piece of Work” should guess again. The new contrived and highly entertaining reality series “Joan and Melissa: Joan Knows Best” (8 p.m., WE) arrives with a whole new chapter for the potty-mouthed comic.

On “Knows,” confirmed New Yorker Joan decides to spend more time with her daughter and grandson and moves to Malibu, Calif. Naturally, complications ensue. Melissa doesn’t like Joan cursing and swearing around her son. For her part, Joan has a curiously moral streak and resents Melissa for keeping her live-in boyfriend a secret.

Not believable for a second, “Knows” is still fun to watch. In one scene, Joan takes her grandson and her daughter’s entourage to the beach where her daughter’s attractive Nanny plays Marilyn to Joan’s Lily Munster. All good reality shows become sitcoms before long — sitcoms with very low budgets.

Tonight’s other highlights

• Sue’s mother (Carol Burnett) shows up on “Glee” (7 p.m., Fox).

• An anniversary ruined on “No Ordinary Family” (7 p.m., ABC).

• President Barack Obama delivers the State of the Union Address (8 p.m., CBS, NBC, Fox, ABC, Fox News, CNN, CNBC, Fox Business, MSNBC).

• Forty candles loom on “Lights Out” (9 p.m., FX).

• “Real Sports with Bryant Gumbel” (9 p.m., HBO) profiles player-turned-broadcaster Troy Aikman and sportswriter Peter King; also, health problems among massive NFL linemen.