Welcome to the boards Lucky
Santa Gertrudis, often referred to as "Gerts", are raised primarily in the hot and humid regions of the south, Texas and parts of the west. However, as you will find, there are Gert raisers in many other areas --- in fact there are CattleToday members from places such as Missouri, Alberta, Canada and I believe upstate New York.
Gert's were originally developed by the King Ranch in south Texas in hopes of "creating" a breed that was capable of doing well in the harsh environment of south Texas (high heat, high humidity, marginal night-time cooling, many bugs & parasites) but that had substantially better carcass qualities than a pure Brahman. They are often referred to as the first American breed, although they are in fact a "composite" that has been stabilized at 3/8 Brahman blood and 5/8 Shorthorn blood and are now are a recognized breed. You'll hear the term "eared cattle", and Gerts are "eared cattle" --- owing to the Brahman influence they will have larger and longer ears than typical Englich or Continental cattle. Many Gert breeders are doing Genestar testing on their animals and through selective breeding are getting some pretty respectable carcasses, although no Brahman cross breed could be expected to "quality grade" as well as a straight Englich breed.
A lot of people are crossbreeding Gerts with Angus or Hereford and part of the reason for that is heterosis, and also to get a 3/16 Brahman 13/16 English animal that can thrive in the local environment and yet produce a very good carcass.
Well, that's all I have time to write at this time. You might want to visit the King Ranch website for a bit of breed history and the story of the most famous Gert, the bull named "Monkey". Also, you might find a brief discussion about what they are currently doing with their Gerts as well as their program to develop the Santa Cruz breed (which is 1/2 Gert, 1/4 Red Angus and 1/4 Gelbvieh). In addition, you may want to check out the Gert main breed assoc. website for additional info. Of course, you should remember that just about any breed assoc. website will paint a pretty rosey picture of a breed, generally without listing the shortcomings.
Hope this helps a bit.