The United States could improve its national budget by nearly $18 billion annually if we taxed and regulated marijuana like alcohol, according to a newly released study from the Cato Institute. “The Budgetary Impact of Ending Drug Prohibition,” by Harvard economist Jeffrey A. Miron and Katherine Waldock, a doctoral candidate at the Stern School of Business at New York University, estimates the amount of money state and federal governments could both save from reduced expenditures and make from tax…