Was public kissing ever a crime in the United States?

Yes, and it still is a crime to kiss in public in some places.

In 1656 in Boston, a Captain Kimble was placed in the stocks for kissing his wife in public on the Sabbath.

To this day, it is illegal in Indiana for a mustached man to “habitually kiss human beings.”

In Cedar Rapids, Iowa, it is still a crime to kiss a stranger.