OK, the second reason for the "division line" is....

[Mark Padgett]

Dr. Naismith told me that the reason the division line is there is because his brother-in-law, Jethro, was the painter who put down the lines on the first gym and he got paid by the line. When Jethro retired, they no longer painted the center line until 1933 when Jethro's grandson took over the business.

OK, who's hiding my meds?