Just copied from the U.S. State Department website:
ENTRY/EXIT REQUIREMENTS FOR U.S. CITIZENS: You need a passport and visa to travel to Turkey. Passports should be valid for at least 90 days from the date of entry into Turkey and must have enough blank space to allow for Turkish entry and exit stamps. If there is not enough space for entry and exit stamps in your passport, you will be denied entry into Turkey.
Also no mention of the e-visa system--only that you buy a visa stamp upon entry…

