It says here that Connect4 can be won by Player $1$ if their first counter goes in the middle column $4$, a draw if they play in columns $3$ or $5$, and Player $1$ loses everywhere else.
As far as I can see, according to the wikipedia article, they cannot win before the $41^{st}$ move, I assume by the Pigeonhole Principle, which makes me think the board size was pre-determined by this fact.
Or can they win before the $41^{st}$ move?
ADDENDUM
There are $\dbinom{42}{21}=538,257,874,440$ final positions. Of course, many are 'game over' before they are realized, and several are impossible. Bonus question: how many complete Connect4 grids have no line of $4$?