Area chart showing the rise of sexually transmitted disease cases in the U.S. for syphilis, gonorrhea, and chlamydia, from 700,000 in 1941 to 2.5 million in 2021. In 1941 there was a rise in syphilis cases and it went up to over 575k during the first recorded outbreak in history. Gonorrhea spiked in the late 1970s, accounting for 94% of all STD cases. Since 1995, there have been more cases of Chlamydia than any other type of STD.