This means $2,000,000,000 in 1865, would equal approximately $33,856,695,573 in 2019.
Apparently the country had more than $2 billion of wartime debt after the Civil War, aka: the War Between the States, the War of the Rebellion, the Great Rebellion, the War for Southern Independence, the War of Northern Aggression, the Freedom War, and the War of Secession, etc.