From the U.S. Postal Service announcement on November 17, 2020:
From the USPS: The long-running series celebrating American lighthouses continues with five new stamps. The mid-Atlantic lighthouses featured in this issuance are: Thomas Point Shoal, MD; Montauk Point, NY; Harbor of Refuge, DE; Navesink, NJ; and Erie Harbor Pierhead, PA. The late Howard Koslow [Wikipedia entry] was the artist for these stamps as well as previous issuances in the Lighthouse series. Mid-Atlantic Lighthouses were the last stamps he illustrated for the Postal Service. The art director was Greg Breeding. [Koslow died in January 2016, so these designs have been “on the shelf” for a while.]
These stamps will be issued August 6th with a ceremony in Highlands, NJ.
Additional information will be posted below the line, with the most recent at the top.
Updated October 4th:
The Scott catalogue numbers for this issue are:
5621 Montauk Point Lighthouse
a. Imperforate
5622 Navesink Twin Lighthouses
a. Imperforate
5623 Erie Harbor Lighthouse
a. Imperforate
5624 Harbor of Refuge Lighthouse
a. Imperforate
5625 Thomas Point Shoal Lighthouse
a. Imperforate
b. Horiz. strip of 5, #5621-5625
c. Imperforate strip of 5, #5621a-5625a
Updated July 7th:
Here are the first-day postmarks for this issue:
The Digital Color Postmark for this issue measures 1.98″ x 1.46″
The pictorial postmark measures 1.83″ x 1.26″
Updated July 7th:
[ceremony information]
New Stamps Shine Light on Mid-Atlantic Lighthouses
WHAT: Lighthouses — with their beauty, mystery and aura of romance — have fascinated and enchanted people for centuries. The Postal Service continues to share in that tradition with Mid-Atlantic Lighthouses Forever stamps, the latest in its continuing series of popular lighthouse stamps.
News of the stamps is being shared with the hashtag #MidAtlanticLighthousestamps.
WHO: Linda Malone, vice president of engineering systems, U.S. Postal Service
WHEN: Friday, Aug. 6, 2021, at noon ET
WHERE:
Twin Lights State Historic Site
2 Light House Road
Highlands, NJ 07732
RSVP: Dedication ceremony attendees are encouraged to RSVP at
usps.com/mid-atlanticlighthouses.
BACKGROUND: For three centuries, the beacons of America’s lighthouses have been guiding mariners through treacherous waters. Though 
the five mid-Atlantic lighthouses being recognized have a common purpose, each has its own unique story — and its own mysterious, eternal appeal.
Authorized by George Washington and completed in 1796, Montauk Point Lighthouse (New York) is one of the oldest lights in continuous operation in the United States.
Navesink (New Jersey) is one of only seven stations in the country to feature two lighthouse towers.
The tower of the Eric Harbor Pierhead Light (Pennsylvania) tapers from its base to its midsection, then rises straight from there to the top, the only lighthouse tower with this shape in the United States.
Harbor of Refuge Lighthouse (Delaware) has stood within the breakwater since 1926 and 
is still an active aid to navigation.
And located in the Chesapeake Bay (Maryland), the Thomas Point Shoal Lighthouse has withstood the elements since 1875.
The Mid-Atlantic Lighthouses stamps are being issued as Forever stamps. These Forever stamps are always equal in value to the current First-Class Mail 1-ounce price.
Updated July 1st from the Postal Bulletin:
On August 6, 2021, in Highlands, NJ, the United States Postal Service® will issue the Mid-Atlantic Lighthouses stamps (Forever® priced at the First-Class Mail® rate) in five designs, in a pressure-sensitive adhesive (PSA) pane of 20 stamps (Item 481000). These stamps will go on sale nationwide August 6, 2021, and must not be sold or canceled before the first-day-of-issue. The Mid-Atlantic Lighthouses pane of 20 stamps may not be split and the stamps may not be sold individually.
The Postal Service™ concludes its long-running series celebrating American lighthouses 
with five new stamps honoring mid-Atlantic lighthouses. Each stamp features an original acrylic painting of one of the following lighthouses:
- Thomas Point Shoal, Maryland;
- Montauk Point, New York;
- Harbor of Refuge, Delaware;
- Navesink, New Jersey; and
- Erie Harbor, Pennsylvania.
Howard Koslow (1924–2016) (right, undated photo from USPS) was the artist for these stamps as well as previous issuances in the Lighthouses series. Mid-Atlantic Lighthouses were the last stamps he illustrated for the Postal Service. Greg Breeding art directed the project.
No automatic distribution.
How to Order the First-Day-of-Issue Postmark:
Customers have 120 days to obtain the first-day-of-issue postmark by mail. They may purchase new stamps at their local Post Office™ or at The Postal Store® website at usps.com/shop. They must affix the stamps to envelopes of their choice, address the envelopes (to themselves or others), and place them in a larger envelope addressed to:
FDOI – Mid-Atlantic Lighthouses Stamps
USPS Stamp Fulfillment Services
8300 NE Underground Drive, Suite 300
Kansas City, MO 64144-9900
After applying the first-day-of-issue postmark, the Postal Service will return the envelopes through the mail. There is no charge for the postmark up to a quantity of 50. There is a 5-cent charge for each additional postmark over 50. All orders must be postmarked by December 6, 2021.