Transgender
One effort to quantify the population gave a "rough estimate" that 0.3 percent of adults in the US are transgender, overlapping to an unknown degree with the estimated 3.5 percent of US adults (1-in-30) who identify as LGBT. More recent studies released in 2016 estimate the proportion of Americans who identify as transgender at 0.5 to 0.6%. This would put the total number of transgender Americans at approximately 1.4 million adults ().
Brigham Young University LGBT history
A BYU Spring 2017 survey taken by 42% of students found that .2% of the 12,602 who completed the survey (or 25 responders) reported their gender identity being transgender or something other than cisgender male or female. For comparison, a 2017 meta-analysis of 20 separate large surveys (with sample sizes ranging from over 30,000 US adults to over 165,000 each) found a conservative estimate of .39% for the portion of US adults who self-identify as transgender.