US Postal Service issued the following announcement on March 23.
Three Previously Announced Stamp Dedication Ceremonies Canceled
The U.S. Postal Service dedications of the following previously announced Forever stamps will be canceled due to the guidance provided by the Centers for Disease Control (CDC) to avoid social gatherings of 10 people or more:
Contemporary Boutonniere and Garden Corsage (April 2, Crestwood, KY)
Earth Day (April 18, Denver, CO)
American Gardens (May 13, Winterthur, DE)
Typically, Postal Service stamp events attract 200 or more attendees. The Postal Service will try to reschedule the dedications at a later date.
These stamps will still be available for purchase on the dates listed above. A follow-up announcement for each stamp will be made prior to the release date.
Customers may purchase these stamps through the Postal Store at usps.com/shopstamps, by calling 800-STAMP24 (800-782-6724), by mail through USA Philatelic and at Post Office locations nationwide.
Requests for first-day-of-issue postmarks and first-day covers will be processed by:
USPS Stamp Fulfillment Services
8300 NE Underground Drive, Suite 300
Kansas City, MO 64144-9900
The Postal Service receives no tax dollars for operating expenses and relies on the sale of postage, products and services to fund its operations.
Original source here.