"Pop" music, in case you forgot, stands for "popular." The term was created to distinguish it from "Classical" music such as opera and symphonic music (Tschaikovsky, Beethoven, Brahms, et al).
Classical music has been around for centuries, and, though popular music has probably been around just as long, much of it was informal, unwritten and passed down from generation to generation.
It wasn't until a young Pennsylvanian, Stephen Foster, wrote a series of popular ditties in the 1850s and became known as the "father of American music" that "pop" music started to take off. Some of Foster's most familiar songs are still well-known today, 160 years later - now that's popular. Foster's better-known works include "Oh! Susanna," "Camptown Races," "Old Folks at Home' (Swanee River), "Jeanie With the Light Brown Hair," and "Beautiful Dreamer."
In the tradition of composers who preceded him (e.g., Mozart) and followed him (Gershwin, Hank Williams), Stephen Foster died young. He was only 37 when died, impoverished (in the days before songwriters copyrighted their works).
After Foster, songwriting as profession grew steadily and popular music became very, well, popular - with the advent of musical revues, musical comedies, and, after Edison - recording these performances.
It wasn't until the advent of Rock and Roll in the early 1950s that popular music began to be split into categories, as I guess traditionalists thought that this crazy music for teenagers didn't deserve to be in the same category as "proper" popular music. Another category which came along in the wake of Rock and Roll was the so-called "race' music (that is, popular songs performed by black artists), which supposedly was meant only for the consumption of Negroes, as they were referred to in those days. Well, that theory didn't last long as white artists started singing the so-called "race music," and eventually, kids of all colors bought music by performers of all colors because it was the "popular" thing to do.
When I was first purchasing records (kids, ask your folks what those were), there were a lot of hit records which were number 1 hits on the charts (again, kids, talk to your folks for translation) which, I suppose, would have been termed "Country" records in later years - songs like "The Battle of New Orleans," "Big John," "Ode to Billie Joe," and "Harper Valley PTA." We didn't think of them as "Country" songs then though - they were just good songs which became popular hits.
And then, somebody thought they needed to separate the music into categories, so us poor consumers would know where we should look to find the music we liked. Next thing you know in Wal-Mart, K-Mart and other discount stores, as well as in actual record stores (kids - check with the folks), albums were placed in bins under categories like "Rock and Roll," "Country," "Jazz," "Folk," "Comedy," and "Popular." Then came specified radio stations - Country stations, Classic Hits, Classic Oldies, etc., etc.
the Country Music Hall of Fame, followed by The Rock and Roll Hall of Fame, and so on.
The irony in all this is that today, in 2012, the classifications seem really blurred to me. When I hear many current "Country" acts, I hear Rock and Roll; many Rock and Roll acts have become countrified, and so on.
This really hit home to me when I watched some of the Academy of Country Music Awards show on TV a week or two ago.
This Country Music Awards show started off with a rocking performance by Carrie Underwood, in a sexy outfit, backed by flashing lights; among other highlights were a song called "Springsteen," the appearance of Bono, the lead singer of the Rock and Roll Hall of Fame group U2, a performance by Lionel Richie, erstwhile lead singer of the R & B group the Commodores, who performed a song from his recent country album, 'Tuskegee' with co-host Blake Shelton, and last but not least - and I wouldn't have believed it if I hadn't seen it with my own eyes - the rock group KISS, in complete makeup.
I guess what I'm saying is - let's go back to the old days, and do away with all these labels. Rock and country artists obviously have mutual respect and admiration for each other, influence each other, and the music they produce is popular with somebody.
Long live Pop Music - in all its various guises.