As we get more DNA data on the male and female lines that are "proven" descendents of those who were FPC or mulatto in the 1800-1870 period, we should get a better picture of their ancestry and a model of how they became FPC or mulatto.
But, too answer your question about classification, I do think that Indian-White mixes tended to be classified as White--perhaps not in the 1st generation, but certainly after that, and that Mulatto-White mixes tended to be classified as White off and on, and Mulatto-Mulatto mixes as Mulatto most of the time--as they should have been under the race laws of most of the States. Now, I can only speak to Hawkins and Hancock counties. But, I believe this applies to AR, NC and KY as well.
I have just gone through a number of new books from the early to mid-1800s and I am convinced more than ever that the terms FPC and Mulatto during that time period were intended to mean part-African from the 1st generation to the 3rd generation--the British classification scheme that we inherited. According to a document that I read from the Island Colonies, you could not tell that someone was part-African if they were less than Octaroon, and that was the basis for the generational rule in the Continental Colonies.
And, according to the Court records of the 1800s, the terms colored and mulatto were part of the problem--e.g., colored and mulatto were intended by State legislatures to mean part African, but the determination was in the eye of the beholder, not actually measurable without records, and often misapplied to those who should not have been classified as mulatto or colored in the legal sense. One of my own great aunts--a Collins is a good example of that--she was said to be colored by her in-laws and that didn't mean Indian.
Getting back to my original point though, I think that the Minors, Fields, and Sizemores of Hawkins and Hancock counties are great examples. We know from the DNA data that the Minors were African, the Sizemores were Indian, and the Fields were White in the male line. In the early census records, the Sizemores and Fields are classified as white, and the Minors as FPC. Now, it would be interesting to see if there is some early census record in KY or NC that classifies them as FPC. The picture that I saw of the KY Sizemore leave no doubt in my mind that he was part Indian--but, was he classified as FPC--although we don't know whether the Sizemores were part African or not through the female line.
Now, I found some interesting books today that help shed light on the public perception of FPCs. I think that these early books are more useful because they reflect the legal and moral beliefs of the time. The last excerpt is especially interesting because it clearly state that in NY you have to be part African to be mulatto.
David Benedict (1813)
A General History of the Baptist Denomination in America and Other Parts of the World
Boston: Manning & Loring
We shall now close this chapter with some general
observations on the condition of the converted negroes,
and the slaves generally in the southern States. We
shall not enter into the merits of slavery, nor dwell
much upon the arguments which are brought for and
against it. We design to go no farther into the investigation of this unhappy policy, than to exhibit something of the circumstances of our African brethren, who are involved in it.
Slaves are the most numerous in Virginia, the two
Carolinas, Georgia, Kentucky, and Tennessee. There
are some in a number of the other States ; but in these
six, the great body of them is found, and Virginia alone
contains about three hundred thousand, almost one-third
of its whole population. And I know not but the proportion
is as great in the five other States. In all the States under consideration there are multitudes of black people and Creoles, who are not slaves. Some are the descendants of manumitted ancestors; many who were born slaves have been liberated by benevolent and conscientious owners, and others have purchased their own freedom.
Pamplet printed in England before 1846 and reprinted in:
James G. Birney (1885)
The American Churches, The Bulwarks of American Slavery, 3rd Edition
I. Of the twenty-six American states, thirteen are
slave states. Of the latter, Maryland, Virginia, Kentucky,
Missouri, and Tennessee (in part), are slave-selling states ; the states south of them are slave-buying and slave-consuming states.
IV. There are in the United States, about 2,487,113
slaves, and 386,069 free people of color. Of the slaves,
80.000 are members of the Methodist church; 80,000 of
the Baptist; and about 40,000 of the other churches.
These church members have no exemption from being
sold by their owners as other slaves are. Instances are
not rare of slaveholding members of churches selling
slaves who are members of the same church with themselves.
And members of churches have followed the
business of slave-auctioneers.
VII. In the slave states a slave cannot be a witness in
any case, civil or criminal, in which a white is a party.
Neither can a free colored person, except in Louisiana.
Ohio, Indiana, and Illinois (free states), make colored
persons incompetent as witnesses in any case in which a
white is a party. In Ohio, a white person can prove his
own ("book") account, not exceeding a certain sum, by
his own oath or affirmation. A colored person cannot, as
against a white. In Ohio the laws regard all who are
mulattoes, or above the grade of mulattoes, as white.
X. The slave states make it penal to teach the slaves
to read. So also some of them to teach the free colored
people to read. Thus a free colored parent may suffer the
penalty for teaching his own children to read even the
Scriptures. None of the slave-holding churches, or religious bodies, so far as is known, have, at any time,
remonstrated with the legislatures against this iniquitous
legislation, or petitioned for its repeal or modification.
Nor have they reproved or questioned such of their members,
as, being also members of the legislatures, sanctioned
such legislation by their votes.
XVI. In the Methodist, Baptist, Presbyterian, and
Episcopal churches, the colored people, during service,
sit in a-particular part of the house, now generally known
as the negro pcw. They are not permitted to sit in any
other, nor to hire or purchase pews as other people, nor
would they be permitted to sit, even if invited, in the pews of white persons. This applies to all colored persons,
whether members or not, and even to licensed ministers of
their respective connections. The "negro pew" is almost
as rigidly kept up in the free states as in the slave.
Interesting Memoirs and Documents Relating to American Slavery (1846)
Narrative of Lewis Clark
Scene at Hamilton Village, N. Y. before 1844 and printed in Liberty Press
Mr. Cyrus Clarke, a brother of the well-known Milton and Lewis Clarke, (all of whom, till within a short time since, for some twenty-five years, were slaves in Kentucky,) mildly, but. firmly, presented his ballot at the town meeting board. Be it known that said Cyrus, as well as his brothers, are white, with only a sprinkling of the African; just enough to make them bright, quick, and intelligent, and scarcely observable in the color except by the keen and scenting slave-holder. Mr. Clarke had all the necessary qualifications of white men to vote. "
Slave. Gentlemen, here is my ballot; I wish to vote. (Board and by-stauders well knowing him, all were aghast— the waters were troubled,—the slave legions were 'up in their
Judge E. You can't vote ! Are you not, and have you
not been a slave ?
Slave. I shall not lie to rote. I am and have been a slave,
so called ; but I wish to vote, and I believe it my right and duty.
Judge E. Slaves can't vote.
Slave. Will you just show me in your books, constitution,
or whatever you call them, where it says a slave can't
Judge E. (Pretending to look over the law, &c., well knowing he was 'used up,') Well, well, you are a colored man, and can't vote without you are worth two-hundred and fifty dollars. (Mr. E. is well known to be very dark; indeed, as dark or darker than Clarke. The current began to set against Mr. E. by murmurs, sneers, laughs, and many other demonstrations of dislike.)
Slave. I am as white as you; and don't you vote?
Judge E. Are you not a, colored man ? and is not your
hair curly ?
Slave. We are both colored men; and all we differ in is,
that you have not the handsome wavy curl; you raise Goat's
wool, and I come, as you see, a little nearer Saxony.
At this time the fire and fun was at its height, and was fast consuming the judge with public opprobrium.
Judge E. I challenge this man's vote, he being a colored
man, and not worth two hundred and fifty dollars.
Friends and foes warmly contested what constituted a colored man by the New York statute. The board finally came to the honorable conclusion that, to be a colored man, he must be at least one half blood African. Mr. Clarke, the SLAVE, then voted, he being nearly full white. I have the history of this transaction from Mr. Clarke, in person. In substance it is as told me, but varying more or less from his language used.