I am a South African travelling to Chicago, I have a valid 10-year visa for the USA but my flight is from Johannesburg to Amsterdam airport, onward to Chicago. Do I need another visa for the fact that I am landing in Amsterdam? I do not have a valid Schengen visa currently.
South Africa is not on the list of countries that must hold an airport transit visa when transiting through the international parts of airports in the Schengen area.
Source: https://home-affairs.ec.europa.eu/policies/schengen-borders-and-visa/visa-policy/who-must-apply-schengen-visa_en and https://www.netherlandsworldwide.nl/visa-the-netherlands/airport-transit-visa
If your itinerary is booked as two separate trips and you need to leave the international parts of the airport to collect checked luggage before your on bound flight, you can use this official tool https://www.netherlandsworldwide.nl/visa-the-netherlands to check if you need a visa in order to clear Immigration.