A set of possible vocal tract shapes for vowels was generated, using a vocal tract model that operates in terms of the two tongue shape parameters determined by Harshman, Ladefoged, and Goldstein (1975) and one parameter of lip opening. Each of the tongue shape parameters was varied through 15 equal steps. Many of the combinations of the two parameters produced impossible distortions of the tongue or tongue shapes associated with consonants, but 147 of the 225 vowel shapes were humanly possible. These are 147 equally spaced vocal tract shapes as defined by the two parameters. Each of these tongue shapes was combined with seven degrees of lip rounding. When the first two formants of these 1029 vowels were plotted, some parts of this formant space are more densely populated than others. There are few vowels with low F1 and low F2. The difference among front vowels, such as those in heed, hid, head, had, can be made simply by varying the vocal tract shape, but the back vowels, such as those in hawed, hood, who’d, require added lip rounding. In the world’s languages there is often an asymmetry in the height of front and back vowels.