There's probably no better place to start than the 1850 Federal Census for Calloway County, Kentucky.
It's really only one of a couple known documents to exist that even remotely addresses the earliest origins of Isaac Jones and is the most common document for people to cite as a source of this info. But how accurate is it really and how much should it be taken at face value?
When the federal census was first designed and laid out in Article 1 Section 2 of the U.S. Constitution back in 1787 and eventually finalized in the passing of the Census Act in 1790, it originally called for U.S. marshals and their assistants to act as enumerators and required they travel the countryside collecting info from house to house; a task that took 18 months when first done in 1790 with a population return of 3.9 million people. The original bill also set the rate of pay for assistants at one dollar for every one hundred and fifty names returned if the people resided in the country and one dollar for every three hundred names returned if the people resided in a city of five thousand or more people. The U.S. marshals were given a one time single payment of anywhere from one hundred to three hundred and fifty dollars. With a system designed around the premise of more names equals more money, if you weren't home when the enumerator happened to come by, your information was most likely obtained from your nearest neighbor regardless of how many miles away and mainly to the best of his knowledge. It wouldn't be long before further legislation had to be passed in an attempt to curtail the massive amounts of false census entries being created by enumerators, but even this wouldn't guarantee the government that they would make every effort to go from house to house. Evidence of this abounds in the various census records taken over the years, with birth years shifting from census to census, frequent name variations being used, and birth locations that vary and jump all over the map.
Speaking of birth locations that vary.....you actually run into this situation in regards to that of Isaac Jones. While the 1850 Census states Isaac was born in Maryland, fortunately for future researchers, his youngest son Joshua Douglas Jones lived to see the 1880 Census. The significant difference between the 1880 Census and all prior census years is that it was in this year that the birth location of your parents was included into the line of questioning. Oddly, Joshua states that both his father and mother were born in North Carolina, not Maryland.
But why put equal weight of truth in the statement of his son as in the words of the man himself? Closer examination of the information presented in the 1850 Census begins to throw up even more red flags pointing even further to the possibility that this info was delivered from a second source who may not have had their facts straight. For starters, how about Isaac's wife? Kissara? When you consider that her name was actually Keziah, and in some instances spelled Kesiah or Kisiah, Kissara barely falls into the realm of even being phonetically correct. In no other instance is it ever spelled like this. Could the enumerator's hearing or spelling really have been that bad? One would think that if this info came directly from her, the spelling would be phonetically closer based on pronunciation alone. Having been able to read and write, it most certainly wouldn't have come from Isaac. The next issue arises with her stated age of 78, which would put her as having been born around 1772. Considering her oldest child, Jane A. Morris, from her one and only prior marriage to James Morris was born in 1817; are we really expected to believe that she had her first child at age 45 and continued on well into her 50's? While I guess not impossible, it's highly unlikely. The 1840 Census even shows her age as being as much as 10 years less than stated in 1850.
With Isaac himself having died at some point between the taking of this census on August 5, 1850 and March of the following year when his estate was being probated, county land records show that he or the family may have known the end was near as early as July of 1849. It is at this time that a deed is drawn up between Isaac's son Joshua and Isaac's son-in-law John Jeffrey who are acting as "the lawful attorneys for Isaac Jones" and Isaac's wife Keziah in which she "relinquishes all claims to his property in exchange for the right to reside until her death on the 160 acre parcel of land they currently live on." Could it be that Isaac had possibly become ill or incapacitated as early as 1849, leaving us with the possibility that someone else provided the data on the 1850 Census? What you're essentially left with here is what amounts to a fifty percent chance he was from Maryland and a fifty percent chance he was from North Carolina. Having examined the possibilities under both contexts, it would seem to me that it's more likely Isaac Jones was born in North Carolina and not Maryland as commonly stated and widely believed. Evidence of this fact I believe can be found in Isaac's involvement with the Methodist religion and his whereabouts prior to arriving in Surry County, North Carolina in 1801.