Because his FATHER naturalized a year AFTER James was born. The chronology is this:
1. Born in the United States on April 21, 1785 to a British national father. James is not even considered a "citizen" of the U.S.
2. James's father naturalized on February 20, 1786.
3. James McClure became as U.S. citizen...NOT because he was born in the U.S., but BECAUSE his father naturalized.
Because his FATHER naturalized a year AFTER James was born.
You have no historical source which says any such thing.
This is typical birtherism. Decide first what spin you want to give to history. Then, claim that that's the way it is, in spite of the fact that you have no evidence to support what you say.
Let's look at what we DO have, shall we?
We have a letter from the Madison administration, signed by James Monroe.
The letter says what it says. It doesn't say what you claim it says. It says what it ACTUALLY says.
And this is what it says:
I quote, in fact, from a posting of the text here at FR, back in September.
Like almost everything birther, it's been gone over before. And, of course, denied by birthers. Why? Because facts don't matter to a birther.
Here it is:
"Sir
I have the honor to enclose several affidavits and certificates just handed to me by Mr. Cheves the Representative in Congress from the City of Charleston proving that James McClure now detained in France as a British Prisoner of War was born in Charleston since the Revolution. To these Papers is annexed a Certificate of W[illiam] Johnson Esq. one of the Justices of the Supreme Court of the United States before whom the affidavits were taken stating “that agreeable to the laws and usage of the United States, the said affidavits and Certificates are sufficient to establish the fact that James M McClure above named is a Citizen of the United States.” As such he must be considered by this Government. You will therefore interpose your good offices in his behalf and obtain his release from confinement as soon as possible.
I have [the honor] James Monroe"
You're not at liberty to simply claim the affidavits said a particular thing without producing REAL EVIDENCE that that's what they said.
But we know what the precise purpose of those affidavits was (and hence have a very good indication of what the CONTENTS of those affidavits was) because Monroe tells us:
"I have the honor to enclose several affidavits and certificates just handed to me by Mr. Cheves the Representative in Congress from the City of Charleston proving that..."
Proving that... what? Proving that James McClure's father was an American citizen?
NO.
"...proving that James McClure now detained in France as a British Prisoner of War was born in Charleston since the Revolution.
That's it. That's what the attached affidavits proved.
They proved that JAMES MCCLURE WAS BORN IN CHARLESTON SINCE THE REVOLUTION.
Was such fact, without any consideration as to the citizenship of McClure's father, sufficient to make him a United States citizen? Monroe tells us:
"To these Papers is annexed a Certificate of W[illiam] Johnson Esq. one of the Justices of the Supreme Court of the United States before whom the affidavits were taken stating “that agreeable to the laws and usage of the United States, the said affidavits and Certificates are sufficient to establish the fact that James M McClure above named is a Citizen of the United States."
So Madison's government consulted with the United States Supreme Court, and got a letter from Supreme Court Justice Johnson which said that the affidavits and certificates THAT PROVED THAT MCCLURE WAS BORN IN CHARLESTON SINCE THE REVOLUTION were SUFFICIENT TO ESTABLISH THE FACT THAT MCCLURE WAS A CITIZEN OF THE UNITED STATES.
If you disagree, then produce your DOCUMENTATION that says, in direct contradiction to the letter from the US government, that the US government considered the citizenship of McClure's father to be a deciding factor. Or, if you can't do that, then apologize for making a false claim.
But you can't do the first, and you won't do the second.
Why? Because THE FACTS DON'T MATTER TO BIRTHERS LIKE YOURSELF. It doesn't matter what the facts are. You will still claim that your false claims are true.
If I wanted to waste my time on it, we could undoubtedly go on with example after example of this. But taking just the first example that comes up, and showing what BS it is, is good enough for purposes of illustration.