Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons. The actual Enumeration shall be made within three Years after the first Meeting of the Congress of the United States, and within every subsequent Term of ten Years, in such Manner as they shall by Law direct. The Number of Representatives shall not exceed one for every thirty Thousand, but each State shall have at Least one Representative; and until such enumeration shall be made, the State of New Hampshire shall be entitled to chuse three, Massachusetts eight, Rhode-Island and Providence Plantations one, Connecticut five, New-York six, New Jersey four, Pennsylvania eight, Delaware one, Maryland six, Virginia ten, North Carolina five, South Carolina five, and Georgia three.
14th Amendment, section 2:
Representatives shall be apportioned among the several States according to their respective numbers, counting the whole number of persons in each State, excluding Indians not taxed. But when the right to vote at any election for the choice of electors for President and Vice President of the United States, Representatives in Congress, the Executive and Judicial officers of a State, or the members of the Legislature thereof, is denied to any of the male inhabitants of such State, being twenty-one(18) years of age, and citizens of the United States, or in any way abridged, except for participation in rebellion, or other crime, the basis of representation therein shall be reduced in the proportion which the number of such male citizens shall bear to the whole number of male citizens twenty-one(18) years of age in such State.
Made some strike through entries to reflect the voting franchise subsequently being granted to 18-year-olds, and members of both genders.
It presents an interesting constitutional argument and interpretation game that can be played on this.
The 14th Amendment seems to be clearly talking about enumerating citizens and other persons (Indians not taxed) with a legal presence in the country. Article 1, section 2 also seems to be
assuming that as well. As prior to about 50 years ago, the idea that the Government would knowingly and willfully allow a sufficiently large population of people to accumulate within its borders who are neither citizens, or legally authorized to be there as to impact the apportionment of congressional seats to be completely mind-boggling.
It probably would have boggled the minds of many people even as late as the early 1990's shortly after the Reagan Amnesty for many illegals.
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The argument could be cut in both directions on that. A very literal interpretation would likely say illegals get counted. But once you start bringing intent into the mix, that's not so clear. Going by recent SCotUS rulings however, Trump would likely lose that fight in court.
But there is "the basis of representation therein shall be reduced in the proportion which the number of such
male citizens shall bear to the whole number of
male citizens
twenty-one(18) years of age in such State" to contend with in both literal readings and intent.
An argument CAN be made that provisions for "the basis of representation therein shall be reduced in the proportion which the number of such" in the 14th Amendment could be applied with regard to non-citizens in the country, as it makes clear that Congressional representation is supposed to be
proportional to the number of (potential) voters in an area(unless otherwise explicitly exempted by the 14th amendment).
If you are not a citizen(or have "a pathway to citizenship"), you simply don't count for the purpose of apportionment. (Because the 14th Amendment
assumed that the United States from then on would only have Native Americans, Citizens, and potential citizens within its borders in any kind of substantial number.
Edit to add: While I think it is an argument that can be made, and there possibly are a few others as well, it doesn't mean I think they are particularly strong ones. But on the same token, I guess I'm getting a taste of how the Abolitionists felt on the matter of enumerating the slaves during the Constitutional Convention.