ST. PAUL — A newly released report has found that hundreds of indigenous women have gone missing or murdered in the U.S. Northern Plains region, including both North Dakota and South Dakota, since 1900. But in reality, that number could be in the thousands.

According to their report released Monday, Nov. 25, the Sovereign Bodies Institute —a nonprofit, indigenous-led research organization studying missing and murdered indigenous women and girls, or MMIWG, has documented 411 such cases from the Dakotas, Montana and Nebraska since 1900.

These Native women and girls hailed from 41 tribal nations and went missing from 142 locations, the majority of which were on rural or reservation land. Thirty-one percent of these girls were under 18 years old when they vanished, and 40% under 21.

The report documents 158 MMIWG cases in South Dakota alone, and 35 in North Dakota.

Of those, 69% of the cases documented occurred since 2000, but the report cautions that this may not be because of a spike in violence. Instead, more awareness and better documentation may be the reason for recent years' higher numbers.

If the number of cases has remained relatively constant since 1900, Sovereign Bodies estimates that the true number could be between 3,500 and 4,700, not accounting for spikes during the boarding school era.

According to the National Congress of American Indians, Native American women experience violence at rates higher than any other race. Over 80% of American Indian and Alaska Native women have experienced violence, and more than half have survived sexual violence, reports the Indian Law Resource Center.

Monday's report points to several reasons for the continuously higher rates of violence against Native women and girls, including jurisdictional disputes, a lack of comprehensive data and insufficient law enforcement response. It also warned of the potential violence that could ensue from the planned construction of the Keystone XL crude oil pipeline by TC Energy (formerly known as TransCanada) through the region.

According to a 2012 report from the United Nations' Human Rights Council, extraction industries operating on Native territories can have "a detrimental impact on indigenous women and girls," resulting in sexual assault, trafficking and exploitation. A 2015 U.S. Department of State report wrote that extraction industries often bring to work sites an influx of workers — often deemed "man camps" — that can increase exploitation of nearby women, including Native women.