Photograph Revenue Stamps

From Wikipedia: "In August 1862, while the Civil War was being waged, the United States government began taxing a variety of goods, services, and legal dealings. As the Civil War progressed, the demand for photographs of family members, soldiers going off to war, and returning war heroes increased dramatically, but not without the notice from the Federal government who saw the advent as an opportunity to raise much needed revenue for the war. On August 1, 1864, the Internal Revenue department passed a photograph tax, requiring photographers to pay a tax on the sale of their photographs. There were no photograph tax stamps issued, so other stamps were substituted (typically, the proprietary or playing card revenue stamps), usually affixed to the back of the photograph. After protests from professional photographers, the tax was repealed on August 1, 1866."

I recently acquired this revenue-stamped tintype photograph.