An unprecedented number of colleges and universities were accused in 2013 of mishandling sexual assault cases, but the only people who know exactly which schools were accused are a handful of attorneys and their staff at the U.S. Department of Education.

In the absence of an official report, The Huffington Post tracked the colleges that are under investigation, face complaints or have received significant criticism for their handling of sexual violence on campus, and plotted them in the map below.

In fiscal year 2013, the U.S. Department of Education's Office for Civil Rights received 30 complaints against colleges and universities alleging failures in the way the schools handled cases of sexual violence. That was nearly double the previous year's tally of 17.

The complaints that the OCR received include allegations specifically related to sexual violence and failures to address them under the gender equity law Title IX, the Education Department disclosed to The Huffington Post. However, the Education Department does not publicly disclose a list of all colleges that are under investigation.

A group of 39 lawmakers penned a letter to the department Wednesday asking that it become more transparent in this regard.

Since Oct. 1 of last year, OCR has already received 13 complaints alleging Title IX violations, making a total of 60 in less than three years.

Colleges and universities receiving federal funding -- which is nearly all of them -- are required under Title IX to respond to incidents of sexual misconduct, assault and harassment on campus, and to have policies in place that attempt to prevent such incidents. The OCR is tasked with enforcing Title IX, and it can open an investigation either proactively or in response to a complaint.

Nearly two dozen schools are currently under investigation, with at least 11 the result of complaints filed by students, faculty and recent alumni. Between 2009 and the present, the OCR opened another 11 proactive investigations with a specific focus on Title IX sexual violence.

If the OCR opens an investigation and finds fault on the part of the higher education institution, the agency often attempts to reach a resolution agreement where it lays out policy reforms the college or university should take. Such an agreement was reached at Yale University in 2012 and at the State University of New York system in 2013. Alternatively, the OCR may refer the case to the U.S. Department of Justice.

In extreme cases, the agency can cut off a school from all federal funding, including Pell grants and student loans. This has never happened.

Click on the list of names or the points on the map to see the schools accused of mishandling sexual assault cases:

Map by Tyler Kingkade/The Huffington Post