March 11th: The Scott catalogue number for this issue is 5157.

Updated January 27th: Here is the digital color postmark for this issue: It measures 2.98 x 1.4 inches.

Updated January 18th:
On January 22, 2017, in Kansas City, MO, the U.S. Postal Service will issue the $23.75 Gateway Arch Priority Mail Express stamp, in one design, in a pressure-sensitive adhesive (PSA) pane of 4 stamps (Item 111300).

The stamp will go on sale nationwide January 22, 2017.

The U.S. Postal Service celebrates the Gateway Arch, in St. Louis, Missouri, with a new Priority Mail Express stamp. The Gateway Arch was built as a memorial to President Thomas Jefferson and the 19th-century traders and pioneers for whom St. Louis was the gateway to the West. The stamp art depicts the majestic stainless-steel arch at sunset in its setting on the banks of the Mississippi River. Towering above the city’s skyline, the Gateway Arch is reflected in the rippling water below, where a barge passes by. Designed by art director Greg Breeding, the stamp features a digital illustration created by Dan Cosgrove.

Stamp Fulfillment Services will make an automatic push distribution to Post Offices of a quantity to cover approximately 30 days of sales.

How to Order the First-Day-of-Issue Postmark:
Customers have 60 days to obtain the first-day-of-issue postmark by mail. They may purchase new stamps at their local Post Office, at The Postal Store website at http://www.usps.com/shop, or by calling 800-782-6724. They should 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 – Gateway Arch Stamp
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 March 22, 2017.

There are two philatelic products for this stamp issue:

• 111316 First-Day Cover, $24.19
• 111321 Digital Color Postmark, $24.90

Technical Specifications:

Issue: Gateway Arch Stamp
Item Number: 111300
Denomination & Type of Issue: $23.75 Priority Mail Express Rate
Format: Pane of 4 (1 design)
Series: N/A
Issue Date & City: January 22, 2017, Kansas City, MO 64108
Art Director: Greg Breeding, Charlottesville, VA
Designer: Greg Breeding, Charlottesville, VA
Typographer: Dan Cosgrove, Chicago, IL
Artist: Dan Cosgrove, Chicago, IL
Modeler: Joseph Sheeran
Manufacturing Process: Offset, Microprint
Printer: Ashton Potter (USA) Ltd. (APU)
Printed at: Williamsville, NY
Press Type: Stevens, Vari-Size Security Press
Stamps per Pane: 4
Print Quantity: 3,000,000 stamps
Paper Type: Nonphosphored Type III, Block Tag Applied
Adhesive Type: Pressure-sensitive
Processed at: Ashton Potter (USA) Ltd. (APU)
Colors: Black, Cyan, Magenta, Yellow
Stamp Orientation: Horizontal
Image Area (w x h): 1.42 x 1.085 in/36.07 x 27.56 mm
Overall Size (w x h): 1.56 x 1.225 in/39.62 x 31.12 mm
Full Pane Size (w x h): 4.12 x 3.45 in/104.65 x 87.63 mm
Plate Size: 20 stamps per revolution
Plate Numbers: “P” followed by four (4) digits
Marginal Markings:
Front: Plate number in two corners of pane
Back: ©2016 USPS • USPS Logo • Four barcodes (111300) • Plate Position Diagram • Promotional Text

Updated January 5th: This stamp will be issued Sunday, January 22nd with no ceremony and a Kansas City, MO, postmark.

from the USPS December 28, 2016:

The Postal Service celebrates the Gateway Arch, in St. Louis, MO, with a new Priority Mail Express stamp. The Gateway Arch was built as a memorial to President Thomas Jefferson and the 19th-century traders and pioneers for whom St. Louis was the gateway to the West. The stamp art depicts the majestic stainless-steel arch at sunset in its setting on the banks of the Mississippi River. Towering above the city’s skyline, the Gateway Arch is reflected in the rippling water below, where a barge passes by. Designed by art director Greg Breeding, the stamp features a digital illustration created by Dan Cosgrove.