Why name "Madison" so popular for girls?

[Grant Barrett]

My niece is named Madison. My sister claims she didn't name the child
after anyone or anything.

Since reading of the name's popularity some time ago, I have
encountered many other Madisons, and their parents, and as far as I can
remember, all seem to believe they plucked the name from the air, that
they didn't borrow it from a television or movie character, an actress,
a favorite book, a friend, or from anyone or anything specific.
"Madison," for whatever reason, appears to have been washed ashore by
the zeigeist.

Grant