Article 92 Chicago Convention
Adherence to Convention
(a) This Convention shall be open for adherence by members of the United Nations and States associated with them, and States which remained neutral during the present world conflict.
(b) Adherence shall be effected by a notification addressed to the Government of the United States of America and shall take effect as from the thirtieth day from the receipt of the notification by the Government of the United States of America, which shall notify all the contracting States.
See also: Article 91 Chicago Convention