Chlamydia was the most common cause of death due to STDs in the US. Overall, between 1996 and 2014 the death rate was 341 per 100,000, followed by 115 for Gonorrhea and 4 deaths for Syphillis. The death rate for 20-24 year olds is especially high at 1800 deaths for Chlamydia, 524 for Gonorrhea and 9 deaths for Syphillis.

See this page for an annual breakdown of the numbers for Chlamydia.