Why did the notation system change?

Back a few decades, I had several books and most games used notation like "Kings Bishop to Queens Bishop 3" but it seems that went away for a sort of battleship grid a-h 1-8 system. When did this occur? And why did it change so drastically?

You have been out of the game for awhile, haven't you?  I blame the computers; I'm sure it's much easier to program.  Notation is much easier to write in tournaments though and once you have the grid memorized, it's just easier all around.  Pretty sure the old USSR led the way and it made its way west.  Anyone know for sure?

Here's a nice article on it, but no history unfortunately....

https://www.chess.com/article/view/chess-notation

You could say that! Thanks for the link

The so-called descriptive notation was used in the USA and the UK, just like inches, feet, gallons, pounds. In other countries the so called algebraic notation was used, just like meter, kilogram...
FIDE has ruled that only the algebraic system is valid now. It is easier for referees to verify claims of e.g. 3-fold repetition. It is also independent of English or any language especially with figurine notation instead of letters per type of piece.

When did that happen? Such a big change

During the past decade there was still a long time veteran playing at my regional teams league in high divisions, the dude was like 80 years old. He never switched to algebraic, and when warned by the arbiters he would just send him to f off.

In the 1970's.

I can imagine why. Having two pieces that start with K could be difficult. (Though I have seen an S used for a Knight, like the Math books...)

#9
Historically K=King and Kt = knight. Later this was simplified to N = knight. So it is K Q R B N P in English. However, in German it would be K D T L S B, in French R D T F C P. Now imagine an arbiter in an international tournament handling a claim of 3 fold repetition based on two scoresheets. Even with two English scoresheets it is difficult to settle a 3 fold repetition claim. In algebraic notation it is much easier to see if like pieces occupy like squares 3 times.

FIDE Laws of Chess:
Appendix C. Algebraic notation
"FIDE recognises for its own tournaments and matches only one system of notation, the Algebraic System, and recommends the use of this uniform chess notation also for chess literature and periodicals. Scoresheets using a notation system other than algebraic may not be used as evidence in cases where normally the scoresheet of a player is used for that purpose. An arbiter who observes that a player is using a notation system other than the algebraic should warn the player of this requirement."

https://handbook.fide.com/chapter/E012018 

The switch from descriptive to algebraic notation only affected the English speaking chess world. Chess players in most other countries had been using some form of algebraic notation for a long time. The switch to a single standard notation was a huge event for the chess publishers, because publishing both a descriptive and algebraic version of a book made it more complicated and expensive. 

Mmm, here it was mainly descriptive until the late 70's. I have a book from 1972 and the author briefly mentioned algebraic and dismissed it as an unnatural method.

Legit didn’t think of the obvious fact of other languages benefiting from Algebraric.

Notation is more convoluted than one might think

https://www.chess.com/article/view/notation-1

https://www.chess.com/blog/batgirl/past-notation