The Joseph H. Treyz collection of patriotic Civil War envelopes contains one hundred and forty-nine envelopes donated by Joseph H. Treyz. Printed during the Civil War, these envelopes were sold to support the Union cause. The envelopes feature patriotic images such as the Union flag, state seals, soldiers, goddesses, depictions of Northern cities, prominent leaders and military officers, and cartoons and caricatures depicting Southern life. The majority of the envelopes include a slogan or poetry supporting the Union.

Publishers identified on the envelopes include the N.Y. Union Envelope Depot; James Gates (Cincinnati, Ohio); J.W. Bond & Co.; Wm. Ridenburgh (New York); Alfred S. Robinson (Hartford, Conn.); [James L.] Magee (Philadelphia); Harpel (Cincinnati); J.M. Whittemore & Co. (Boston); Mumford & Co. (Cincinnati, Ohio); J.E. Tilton & Co. (Boston); Young, Lockwood & Co. Prs. (Buffalo); T. Lynch (New York); J.G. Wells (New York); Brown & Ryan (New York); and Charles Magnus (New York).

James L. Magee and Charles Magnus were well known lithographers/engravers and during the war expanded their products to include envelopes promoting the Union. Magee was also known for his caricatures and cartoons on the envelope covers.

The envelopes range in size from 4¾ x 2½ to 3¼ x 6 inches. Most of the envelopes are beige in color, with a few that are yellow, blue, or pink. The images are either in black and white, or colored (blue, red, or a combination of red, white and blue). The envelopes have been glued onto individual pages with six envelopes per page (three on each side).

The envelopes have been scanned and are available digitally via New York Heritage.