How many transgender people are there? Until the year 2000 we only had estimates from medical clinics which grossly understated the population frequencies of being transgender, being transsexual and transgender genital plastic surgery. In 2000, the first mathematical estimation models were constructed using data and the results were surprising. Since then they have been confirmed by surveys in which being transgender is asked directly or can be inferred from health surveys. But the fate of future US government surveys is in doubt. Transgender people will not be counted in the 2020 US Census and questions identifying transgender people have been stripped from important surveys. So what is the best current scientific estimates available?