Civil War Envelope $150

This 5 1/4" x 3" envelope was mailed in the 1860's from Washington, DC to New York with an upside-down 3 cent stamp. (The last digit of the year on the postmark is illegible.)

It was printed with an interesting graphic of a Union soldier and the slogan "The Union Forever", below which is "97th Regt. N.Y. Vols. Conkling Rifles".