I read in the Turkey guidebook that visitors arw required to apply for an eVisa before visiting Turkey. Has this changed since publication in 2021? It looks like the U.S. State Department website says visas are not necessary on an ordinary passport.
Yes, it has changed officially, as of December. In practice, the eVisa website for Turkey has not yet been updated.
ETA: perhaps the eVisa website will not be changed as (per the web page for the Turkish Embassy in the US) "Official passport holders are required to have visa to enter Türkiye." So the US (U.S.A as it is listed in the drop-down) will seemingly remain an option.
Ah, I found the updated language on the eVisa website:
https://www.mfa.gov.tr/visa-information-for-foreigners.en.mfa
United States of America: Official passport holders are required to have visa to enter Türkiye. Ordinary passport holders (e.g., most tourists) are exempted from visa up to 90 days in any 180-day period.