John Adams saw this coming:
The same reasoning which will induce you to admit all men who have no property to vote with those who have, for those laws which affect the person, will prove that you ought to admit women and children; for, generally speaking, women and children have as good judgments, and as independent minds, as those men who are wholly destitute of property; these last being to all intents and purposes as much dependent upon others who will please to feed, clothe, and employ them, as women are upon their husbands, or children on their parents.
…
Society can be governed only by general rules. Government cannot accommodate itself to every particular case as it happens, nor to the circumstances of particular persons. It must establish general comprehensive regulations for cases and persons. The only question is, which general rule will accommodate most cases and most persons.
Depend upon it, sir, it is dangerous to open so fruitful a source of controversy and altercation as would be opened by attempting to alter the qualifications of voters; there will be no end of it. New claims will arise; women will demand a vote; lads from twelve to twenty-one will think their rights not enough attended to; and every man who has not a farthing will demand an equal voice with any other, in all acts of state. It tends to confound and destroy all distinctions and prostrate all ranks to one common level.
The full (I think) letter is here. It’s excerpted near the beginning of Keyssar, The Right to Vote, which, coincidentally I’m currently reading.