American wizards are even more underground in third Pottermore story

A small leak to the descendent of a Scourer was nearly disastrous to the American wizarding world.

In J.K. Rowling's third entry in her "Magic in North America" series on Pottermore, she delves into the strict segregation between the No-Maj and the magical community, stemming from a catastrophic breach in 1790 that nearly exposed the magical government, MACUSA, and the rest of the wizarding community.

A dim-witted daughter of the president of MACUSA, Dorcus Rappaport, was seduced by a No-Maj and Scourer descendent, and unwittingly gave him the information on several key magical locations. As the Scourer descendent, Bartholemew Barebone, readied his torches and pitchforks, some innocent No-Maj's got caught in the line of fire, and Barebone was arrested without magical intervention.

Blowback from the incident caused MACUSA President Emily Rappaport to pass a law separating the wizarding community and No-Maj's, to higher degrees than was seen even in the U.K. and Europe. Rowling's story says:

Dorcus’s indiscretions led to the introduction of Rappaport’s Law. Rappaport’s Law enforced strict segregation between the No-Maj and wizarding communities. Wizards were no longer allowed to befriend or marry No-Majs. Penalties for fraternising with No-Majs were harsh. Communication with No-Majs was limited to that necessary to perform daily activities.

Read the rest of the entry, "Rappaport's Law," here.