We are just now getting this letter from the Chinese Embassy, but it applies to all US travelers!
“The U.S. Embassy in Beijing, China, would like to inform U.S. Citizens that the U.S. Government will no longer be able to add additional visa pages to U.S. passports starting January 1, 2016. Instead, 52-page passport books will be issued at no extra cost. This worldwide change enhances the security of U.S. passports.
U.S. Citizens who require extra pages in their U.S. passports should make an appointment to come to the U.S. Embassy’s American Citizen Services unit before December 31, 2015. Once the change goes into effect worldwide, we recommend that U.S. Citizens who travel frequently renew their passports early to ensure they have enough blank pages for visa stamps from other countries.”
To make an appointment: visit the US Embassy’s webpage
See travel.state.gov for more information on entry, exit, and foreign visa requirements.