Original 1st printing 13 x 19&7/8" double-sided concert poster for a pair of 1970 concerts held at Mammoth Gardens in Denver, CO featuring the Grateful Dead appearing with John Hammond from 4/24-25 and Jethro Tull appearing with Zephyr (featuring Tommy Bolin) and Clouds (with Billy Cobham) from 4/17-18.

 Art by B. Warren, medium-thick textured index stock poster is in used (B-) condition; there are a series of semi-pronounced horizontal roll bends traversing the image area, one side of the poster has a series of tape residue marks going around the outer margins, along with a few decent-sized surface stains, a couple of stray pieces of tape, a moderate amount of surface wear, light toning, a couple of small pulls, multiple pin holes in the corners, etc.... I am almost 100% certain this example was taken down from outdoor public display in 1970.

 Conditional issues aside, it is still a somewhat hard-to-find (only the second example I have seen) low-run 1st printing regional Dead concert poster from an incredibly fertile period for the band. A tape from the 4/24 show exists (a little rough in sound quality, but all there), check it out HERE:

https://archive.org/details/gd70-04-24.aud.hanno.19531.sbeok.shnf