The Hagler family of North Carolina is shown in many online genealogies to descend from Hans Jacob Haegler, who may have been born about 1700 or earlier, and immigrated with his wife Maria Mohler and some of their children in the mid-1700s from Basel, Switzerland to North America. Hans Jacob and Maria settled in Virginia, but at least two of their possible Swiss-born sons, John Hagler (1726-1772), who is often called Ol' John, and his possible brother Johannes (John) Hagler (1733-1816) eventually made their way to North Carolina, where in 1765 they both acquired land - Ol' John settling on Dutch Buffalo Creek, and the other John settling in the Pee Dee River Valley. Whether these two John Haglers are truely brothers is not known with any certainty, but it seems likely they are somehow related. Other Hagler cousins or brothers from Virginia may have also made the trek south to the Carolinas with these two John Haglers, but their names are not known to us. From these pioneers descend at least two of the branches of the Hagler Family that we know about.

Branch I - Ol' John Hagler (d. 1772) is the patriarch of one branch of the family, and one of his sons is the well-known John "the Cripple" (c.1740/50-1811) Hagler of Cabarrus County, North Carolina. John the Cripple was born with a club foot, and his wife was a close relative of future U.S. president James K. Polk. John the Cripple's father Ol' John Hagler bought 255 acres of land along Dutch Buffalo Creek in what was then Mecklenburg County, North Carolina, and the 1997 book "Trail of the Haglers" by Travis Jackson Hagler tells the story of them and their descendants. John the Cripple lived at Haglers Ford, which crossed the Rocky River in that part of Mecklenburg County that in 1792 became Cabarrus County. Although he had several brothers, John the Cripple is the best known of the lot, and he is to be identified with what we call the Cabarrus County branch of the Hagler family. Of John the Cripple's many brothers, his older brother Jacob needs further mention as he was a prominent and well-respected man who settled on Dutch Buffalo Creek near his father and younger brother. He is said to have remained married to the same woman for 74 years, and to have had many descendants. Because the name Jacob is common among all three branches of the Hagler family - as are the names Peter, Paul and John - many genealogies seem to confuse this Jacob with his cousin of the same name who figures in the Tennessee branch of the family that follows next.

Branch II - John Hagler (d. 1816) of the Pee Dee Valley is the patriarch of another branch of the family. Two of his sons named John (1760/62-1836) and Jacob (1768-1828) were born in the Pee Dee Valley of Anson County, North Carolina and came north as children with their father in the late 1770s to a part of Wilkes County that today is part of Caldwell County. They then continued west as young men in the early 1800s to Henry and Stewart counties in Tennessee. These pioneers represent the Tennessee branch of Hagler family. Some members of this branch remained in Tennessee, but Jacob later went west with his son William "Billie" Robbins Hagler (1787-1832), and his nephews Cleveland Hagler (1782-1871) and Benjamin Jones Hagler (1791-1865) to Madison County, Illinois, where they are counted in the 1818 state census that was conducted for the admission of Illinois into the Union. Cleveland and Benjamin were the sons of Jacob's brother John, and Cleveland also married Jacob's daughter Nancy. John (d. 1836) stayed at first in Tennessee, but later joined his brother and two sons in Illinois. Some of these restless Tennessee Haglers then continued west to Iowa.

Branch III - An elusive pioneer known to us as Jacob (or Isaac?) Hagler (b. c.1750?) is thought by some to be the father of the Jackson County branch of the Hagler family of southern Illinois. He is also said by some to be a grandson of the Hans Jacob Hagler who came from Switzerland to Virginia in the mid 1700s, but as with Ol' John Hagler of Dutch Buffalo Creek and his contemporary John Hagler of the Pee Dee Valley the tie to Hans Jacob Hagler of Switzerland is difficult to document. Although there is no hard evidence of interaction between the Haglers of Dutch Buffalo Creek, the Haglers of the Pee Dee River Valley who eventually settled in Tennessee, and the Haglers of southern Illinois, it seems reasonable that they are all somehow related. As already noted, the names Jacob, Peter, Paul and John are common to all three branches of the Hagler family, and all three have roots in similar parts of North Carolina, which creates considerable confusion among the many Hagler genealogies to found on the internet. Suffice it to say that the origins of the southern Illinois branch of the family are not known with any certainty, despite claims to the contrary, and that connections between the three branches of the family at this time are unproven assumptions based on circumstantial evidence.