The Scottish Rite is one of the appendant bodies of Freemasonry that a Master Mason may join for further exposure to the principles of Freemasonry. A Rite is a series of progressive degrees that are conferred by various Masonic organizations or bodies, each of which operates under the control of its own central authority. This appendant body of Freemasonry allows Master Masons to expand their masonic knowledge through the performance of additional degrees at annual reunions. These degrees allow masons to become 32 degree masons. The 33 degree is purely ceremonial and is conferred by the Supreme Council upon members of the Rite in recognition of outstanding service to the Rite, or in public life, to the principles taught in the Degrees.
In England and some other countries, while the Scottish Rite is not accorded official recognition by the Grand Lodge, only a recognised Freemason may join and there is no prohibition against his doing so. In the United States, however, the Scottish Rite is officially recognized by Grand Lodges as an extension of the degrees of Freemasonry. “The Scottish Rite builds upon the ethical teachings and philosophy offered in the Craft (or Blue) Lodge, through dramatic presentation of the individual degrees.” (1)
In the USA it is broken up into two organizations, the Northern Masonic Jurisdiction and the Southern Jurisdiction.
The NMJ was founded in 1813, 48 years before the US Civil War. It includes 15 states and was created simply for logistical reasons to administer the rite more efficiently over such a large geographic area at a time before automobiles.
The SJ was founded in 1801 and includes all other states and territories on the USA not covered by the NMJ. Its headquarter is at the House of the Temple located in Washington DC.
(1) Wikipedia <https://en.wikipedia.org/wiki/Scottish_Rite>
https://scottishrite.org/
https://scottishritenmj.org/