Tennis: When and where did 30-all (and 15-all) start transitioning to the counterintuitive 30-up (and 15-up)?

At my tennis club in the suburbs of DC, about half the players (when serving) call 30-up when the score is 30-30, and the rest call out the more intuitive 30-all.

To my mind, 30-up logically means the server has 30 and the receiver has zero. Note that the server's score is always given first. (Except in court tennis, see below.)

Wikipedia, Tennis Scoring System says:

.... when each side has won one, or two, points, the score is described as "15-all" and "30-all" (or "15-up" and "30-up") .....

So, according to Wikipedia at least, 30-up is an alternative term to the more traditional 30-all.

I played court tennis, aka real tennis, the predecessor game to today's tennis, for five years, and I never heard 30-up or indeed 30-all. I always heard the score fully called out, e.g. 30-30. Thus, 30-up (or 15-up) probably came into being in the past 150 years, after modern tennis was invented. (Real tennis originated in medieval times.)

I know language changes, not always logically, but this seems a particularly non-intuitive change, and I have wondered for some time how it happened and why 30-up (15-up) caught on.

It probably started in a different sport such as baseball.

For example, the 8 June 1906 St. Louis Post-Dispatch at page 16 says:

With the score tied 3 up in the ninth inning and Wallace on third, Powell ripped a hot one between short and third.

It would be more logical to originate in golf, where you could be "tied n up" or "tied n down". For example, from the 29 January 1963 Arizona Republic:

Match vs. par Class A, Alta Harford, Geneva Fox, tied, 2 up. Class B, Ellen Getz 1 up. Class C, Jeannlg Springer, Vivian Mills, tied, 2 down. Class D, Rose Fontaine, 1 down.

For an older golf example see the 16 July 1916 Houston Post:

In the third division, E. U. Neville and J. O. Maillot tied, 2 up.

For tennis, as far as scoring points, the earliest example I see is in the August 1939 Boys' Life at page 11:

"Thirty-fifteen," Ace said disapprovingly. ... Bill zipped over a beautiful serve in the most casual manner possible, and Woody returned it with a forehand drive that cut down the center line and flattened out like a pancake. "Nice one" said Bill breaking his silence. "Thirty up."

The 1971 book Tennis attempts to stop people from saying "up":

Rather than saying "15 up" or "30 up" to denote an equal score, the term all is used. Therefore, if each player had won one point, the score would be "15 all"; if each had won two points, the score would be "30 all."

However, the 1991 Tennis for Beginning and Intermediate Players says:

Tie scores (one point each or two points each) are usually expressed by “all” or “up”, such as fifteen all, fifteen up, thirty all or thirty up. If the score is tied at three points each, the score is quoted as deuce, instead of forty all or forty up.

Up, as a word, is very productive in sports.

From the OED we have two scoring related definitions, though neither of these have the meaning we seek.

12.c. (At) the number or limit agreed upon as the score or game.

13.d. (So many points, etc.) in advance of a competitor.

For 12.c. as applied to tennis see Julian Marshall's The Annals of Tennis. In a discussion of which side is preferable in the game of Long Fives, Marshall calls games scored to eight "eight-up" and games scored to eleven "eleven-up."

This potentially could be the source of using [number] up to indicate a tie: if a game requires two points to win both competitors could be at the agreed upon scoring limit (e.g. both at 11, or 11-up). This would indicate a tie in the last moments of the game, but could have drifted to discuss all ties.

I, though, find Jeff Zeitlin's hypothesis in the question's comments more likely, that the preposition has moved right of the number from "tied up". "Tied up at fifteen" becomes "tied fifteen-up."

In 2007 Christopher Davies wrote that the [number] up usage was American.

The terms fifteen up, meaning fifteen apiece and all tied up, are one used in the US.

While this finding does not necessarily mean the usage is originally American, it did make me wonder if the application in tennis derives from other American sports.

I attempted a search for the first recorded use of any number and up to indicate a tie. Searching "[number] up" and any additional search term related to sports is not helpful because much more common is language that refers to a lead, not a tie.

Instead I searched "tied [number] up" for every number from 1 to 15.

The first earliest result I found was, in fact, from tennis. It comes from a 1937 volume of the Michiganensian:

The meet with O.S.U. at Columbus was stopped short by rain with the score tied, two up.

While this scoring is related to tennis it refers to sets, not points. Whether or not this instance is the first written recording, this term was likely spoken far earlier. Still, this mention indicates that perhaps the usage did not begin with reference to tennis points. This also challenges any (as of yet unpresented) hypothesis regarding the hands of a scoring clock.

I have an observation regarding the the scoreboard. Each player/pair's score has a seperate 'marker' on the board. When it is 30 all - both markers will be 30 - so it might have been referred to as ' 30's are up' which in turn may have been shortened to '30 up' over time.

I tried looking for a glossary of the terms used by the scorekeeper - but couldn't find one.

Other sport's scorekeepers came up in the search. Baseball was one, and as the question refers to an American club I would not be surprised if this term migrated from one of the commonly played games in the States.

The only example I can give is that certain sporting terminology has become part of our language.

https://en.wikipedia.org/wiki/List_of_sports_idioms

As you seem to want things referenced I put that in as a bookmark until I can find something more appropriate. It was an easy option to show that words migrate. For the subject of the enquiry I think I would need a more sport related example:- poor example - the use of 'advantage' during coverage of penalty shoot outs. I'll have to come back to this over the weekend.