The website of the Los Angeles Times said this on what would have been its homepage: "Unfortunately, our website is currently unavailable in most European countries.
"We are engaged on the issue and committed to looking at options that support our full range of digital offerings to the EU market.
"We continue to identify technical compliance solutions that will provide all readers with our award-winning journalism."
When one typed in the homepage address, it went to an URL that read https://www.washingtonpost.com/gdpr-consent/.
There was no change at The New York Times or at The Wall Street Journal. The latter has always had a paywall.
Websites owned by Oath, the company formed from the amalgamation of Yahoo! and AOL, also did not let users in without consenting to an agreement.
The Yahoo! site said: "Due to EU data protection laws, we (Oath), our vendors and our partners need your consent to set cookies on your device to use your search, location and browsing data to understand your interests and personalise and measure ads on our products. Oath will also provide personalised ads to you on our partners' products."
The site of the US National Public Radio gave readers a choice: either agree to receive cookies or else use a text version of the site.
The free-to-play gameshow MOBA-shooter Super Monday Night Combat had said on 1 May that it would shut down once the GDPR took effect.
But all these precautions may be of no effect as the GDPR covers the data of European citizens no matter where they are based.