to quote the SCP Foundation wiki:
"SCP-4006 is a probabilistic anomaly affecting the state of Massachusetts, USA. SCP-4006 works to perpetuate the idea that Massachusetts is a populated state with a government, infrastructure, economy, various population centers, et cetera. Due to this, the true nature of Massachusetts is entirely unknown to the public; Massachusetts has no history of human occupation. All effects of SCP-4006 are in and of themselves mundane events, though highly improbable. It is the pervasiveness and frequency of these nigh incalculably low probability events, and their collaboration to effectively spread misinformation about Massachusetts, that earns SCP-4006 anomalous recognition. Why several SCP Foundation researchers were immune to the effects of SCP-4006 and were able to discover it (and subsequently spread the information to others) is unclear."