There was a huge information dump recently on Pottermore. It's all about magical society in America. It's in several parts. Here we go:
-Fourteenth and Seventeenth Century
Though European explorers called it 'the New World' when they first reached the continent, wizards had known about America long before Muggles (Note: while every nationality has its own term for 'Muggle,' the American community uses the slang term No-Maj, short for 'No Magic'). Various modes of magical travel – brooms and Apparition among them – not to mention visions and premonitions, meant that even far-flung wizarding communities were in contact with each other from the Middle Ages onwards.
The Native American magical community and those of Europe and Africa had known about each other long before the immigration of European No-Majs in the seventeenth century. They were already aware of the many similarities between their communities. Certain families were clearly 'magical', and magic also appeared unexpectedly in families where hitherto there had been no known witch or wizard. The overall ratio of wizards to non-wizards seemed consistent across populations, as did the attitudes of No-Majs, wherever they were born. In the Native American community, some witches and wizards were accepted and even lauded within their tribes, gaining reputations for healing as medicine men, or outstanding hunters. However, others were stigmatised for their beliefs, often on the basis that they were possessed by malevolent spirits.
The legend of the Native American 'skin walker' – an evil witch or wizard that can transform into an animal at will – has its basis in fact. A legend grew up around the Native American Animagi, that they had sacrificed close family members to gain their powers of transformation. In fact, the majority of Animagi assumed animal forms to escape persecution or to hunt for the tribe. Such derogatory rumours often originated with No-Maj medicine men, who were sometimes faking magical powers themselves, and fearful of exposure.
The Native American wizarding community was particularly gifted in animal and plant magic, its potions in particular being of a sophistication beyond much that was known in Europe. The most glaring difference between magic practised by Native Americans and the wizards of Europe was the absence of a wand.
The magic wand originated in Europe. Wands channel magic so as to make its effects both more precise and more powerful, although it is generally held to be a mark of the very greatest witches and wizards that they have also been able to produce wandless magic of a very high quality. As the Native American Animagi and potion-makers demonstrated, wandless magic can attain great complexity, but Charms and Transfiguration are very difficult without one.
-Seventeenth Century and Beyond
As No-Maj Europeans began to emigrate to the New World, more witches and wizards of European origin also came to settle in America. Like their No-Maj counterparts, they had a variety of reasons for leaving their countries of origin. Some were driven by a sense of adventure, but most were running away: sometimes from persecution by No-Majs, sometimes from a fellow witch or wizard, but also from the wizarding authorities. The latter sought to blend in among the increasing tide of No-Majs, or hide among the Native American wizarding population, who were generally welcoming and protective of their European brethren.
From the first, however, it was clear that the New World was to be a harsher environment for witches and wizards than the Old World. There were three main reasons for this.
Firstly, like their No-Maj counterparts, they had come to a country with few amenities, except those they made themselves. Back home, they had only to visit the local Apothecary to find the necessities for potions: here, they had to forage among unfamiliar magical plants. There were no established wandmakers, and Ilvermorny School of Witchcraft and Wizardry, which would one day rank among the greatest magical establishments in the world, was at that time no more than a rough shack containing two teachers and two students.
