Lent is the Catholic season of fasting and sacrifice and giving up indulgences for a period lasting 40 days and ending on Easter Sunday.
No one knows for certain where the custom began of gorging one's self just before Ash Wednesday, which is the official start of the Lenten season. The tradition was probably the result of the merging of Pagan and Christian customs like other Catholic-Christian holdays we celebrate today, including Halloween, Christmas and Easter.
When we think about the timing of Lent, the season begins in mid-winter and ends just before Spring. In the Old World this would have meant that you needed to make food and supplies last through the winter in order to survive until spring, so the timing of Lent certianly made sense.
Most pagan beliefs based their traditions and celebrations on observations of their natural world. The idea of fatting up just before a long winter is not exclusively a human idea. Bears fatten up just before hibernating for winter, while squirrels hide nuts to see them through until spring. So the timing and concept of Lent may well have been out of necessity to ensure supplies and food lasted in the town or village until the next growing season, while the idea of partying and fatting up just before the long winter made perfect sense to our instincts, and appealed to our human nature for celebration and merriment.
So Mardi Gras is a season of celebrations beginning shortly after the first of the new year, and climaxing on Mardi Gras Day (Fat Tuesday) just before the long Lenten season of sacrifice.
The first official recorded Mardi Gras observance in America occured in Louisiana on Tuesday, March 3, 1699. The place was a camp established by d'Iberville, located 60 miles down river from what is today New Orleans. The camp was thus named, "Point du Mardi Gras" and the neighboring tributary "Bayou Mardi Gras" in honor of the new discovery coinciding with the French-Catholic holiday. The river they had discovered turned out to be the mouth of the Mississippi River, which was already claimed for France by the French explorer René-Robert Cavelier, Sieur de La Salle in 1683, but La Salle had failed to find the mouth of the Mississippi leading to the Gulf of Mexico. Bayou Mardi Gras turned out to be major discovery for the French.
d'Iberville's first landing occured somewhere on the shores between what is today known as Biloxi and Ocean Springs, Mississippi. He sailed deliberately around and passed the newley established Spanish fort located in Pensacola, Florida in order to find the mouth of the Mississippi River, which La Salle failed to do on his prior expedition. The French were on a mission to build an empire in the new world by linking the Saint Lawrence and Mississippi river basins.
d'Iberville established the fist capital of the Louisiana Territory in Biloxi, Mississippi. He later moved the capital to Mobile, Alabama in 1702 after Fort Mobile was complete. This is why both Alabama and Mississippi also claim to be the birthplace of Mardi Gras celebrations in America.
The first organized Mardi Gras celebrations in America occurred in 1703 in Mobile, Alabama by the first settlers of the newly established French Capital. The first official social clubs known today as "mystic societies" or "krewes", were established shortly after in 1711.