The official currency in Texas is the United States Dollar (USD, $).
Texas has used the U.S. dollar since annexation in 1845. Before that, as the Republic of Texas (1836–1845), it issued its own paper money ("Texas redbacks") and used Spanish/Mexican silver coins, U.S. coins, and private bank notes. The Texas dollar collapsed due to inflation.
Today, no separate currency exists. All transactions use Federal Reserve Notes. Texas-chartered banks issue deposits denominated in USD. The Federal Reserve Bank of Dallas (11th District) serves the region.