I've posted in some random threads about these, but thought I would share these in a single thread.
Rule 4.03 in in the official MLB rule book discusses the exchange of line-up cards. Each team's manager provides the umpire with his line-up in duplicate. A copy from each team is kept by the umpire and a copy is given to the manager of the other team. This process establishes the batting order for each team and teams are not allowed to bat out of order.
What this means is that for each game there are 3 line-up cards for each team. Generally there is one hand-written copy and 2 carbon copies that are used. Line-up cards have been used since the 1930's and possibly earlier since the rule that line-ups need to be in place before the game existed before 1900.
A couple of years back I came across a couple of line-up cards on eBay and thought it would make a really cool collection. I decided to focus primarily on managers who have made the HOF (whether due to their career as a manager, player or any other reason). There are always some line-up cards floating around eBay, but they are surprisingly hard to find, even for fairly modern managers.
I've been able to find quite a few of the modern managers including Bobby Cox, Sparky Anderson, Dick Williams, Tony LaRussa (from the 98 team on which McGwire broke the HR record). I've also been able to pick up a couple from a little earlier including Whitey Herzog (from the WS Champion season in 1982 and an Al (Red) Schoendienst from 1971. From that era I was also able to pick up a really nice Ted Williams signed line-up card from his time managing the Texas Rangers.
Going back a little further I've been lucky enough to find a few from players that I imagine only a few still exist (I assume back in the day given the flimsy paper these were written on and the fact that no one assumed any of this would be worth something, that very few were preserved.)
One is a Lefty O'Doul line-up card from when he managed the San Francisco Seals back in 1950. The Seals played in the Independent League on the Pacific Coast League from 1903 until 1957 when the Giants moved to San Francisco.
The other two were the first 2 that got me started on this collection and come from the 1930's. One is signed by HOF manager Bucky Harris, and the other by one of the greatest pitchers of all-time: Walter Johnson.
I have a couple more on their way in and look forward to sharing. I find this a super interesting item to collect and they are really challenging to hunt down.
I also have quite a few copies of more modern line-up cards (including many carbon copies) that I'd be happy to trade if anyone has any one's that I need (or potentially sell in the right situation).