The Biden administration demanded governors in 16 states address a more than $12 billion funding disparity between land-grant Historically Black Colleges and Universities (HBCUs) and their non-HBCU counterparts, according to the US Department of Agriculture.

In joint letters sent to the governors of each state Monday, Secretary of Education Miguel Cardona and Secretary of Agriculture Tom Vilsack noted that HBCUs have "not been able to advance in ways that are on par" with other land-grant institutions in those states "in large part due to unbalanced funding."

A land-grant institution is a college or university that provides education in the fields of agriculture, science, military science and engineering. The schools were also built on federal land or funded with proceeds from the sale of federal land that was granted to state governments. By law, according to the USDA, these schools and their HBCU counterparts "were required to receive equitable distribution" of funds from their state governments.

Letters were sent to the governors of Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, Missouri, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia.

"Unacceptable funding inequities have forced many of our nation's distinguished Historically Black Colleges and Universities to operate with inadequate resources and delay critical investments in everything from campus infrastructure to research and development to student support services," Cardona said in a statement.

Land-grant institutions were first created by the Morrill Act of 1862 to help people pursue higher education in farming and mechanical skills. The legislation was amended in 1890 and again in 1994 to "address educational inequality among African Americans and Native Americans," the agency said.

To calculate the amount each HBCU would have received if funds were provided equally, administration officials used data from the National Center for Education Statistics Integrated Postsecondary Education Survey 1987-2020, the USDA said in a news release.

The "unequitable appropriated funding" of the 1890 institutions in each state ranged from $172 million to $2.1 billion, according to the release.

There more than 100 land-grant institutions in 57 states and territories, according to the Department of Agriculture. Only 18 states have land-grant HBCUs. The USDA noted that only Delaware and Ohio have "equitably funded their respective universities."

CNN has reached out to the 16 states that received letters from the federal government.

Jay Dardenne, commissioner for the Louisiana Division of Administration, confirmed to CNN that his office received the letter from Secretaries Cardona and Vilsack. Southern University and A&M College in Baton Rouge are both land-grant HBCUs in the state.

Dardenne said in a statement the source of the funding estimates included in the secretaries' letter was "unclear." He added that his office has been directed by Gov. John Bel Edwards to meet with the secretaries and learn more about it.

"This administration has consistently provided the federal funding match requirement for Southern University Ag Center as well as the additional funding to stabilize and sustain Southern University New Orleans. However, we recognize that more work needs to be done to fully fund higher education," Dardenne said in a statement.

When asked about the letters, Carter Elliott, a spokesman for Maryland Gov. Wes Moore told CNN the governor "has been a strong advocate" for HBCUs in the state and has directed millions of dollars in funding to assist them.

"Governor Moore will continue to support these life-changing colleges and universities that make Maryland a more equitable and competitive state," Elliott said in a statement.

Secretary Vilsack said the discrepancies in funding should be "a clarion call" for governors to act.

"We need governors to help us invest in their states' HBCU's at the equitable level their students deserve, and reflective of all they contribute to our society and economy," Vilsack said in a statement.

The issue of underfunding of land-grant HBCU's has been a topic of debate for years. In 2022, CNN previously reported six students at Florida Agricultural and Mechanical University filed a federal lawsuit against the state claiming the institution has been underfunded for decades.