Today, first-class mail is often carried by planes, but before 1977, air mail was a distinct service from first-class mail, and a sender paid a handsome premium for speedy delivery.
The first official airmail route was inaugurated on May 15, 1918, between New York and Washington, DC, and it cost 24-cents to send a one-ounce letter. That total included a 10-cent special delivery fee plus 14-cents of airmail postage. A first-class letter via ground service would have cost just 2-cents.
Rates on that route came down rapidly, however, and by the end of 1918, it cost just 6-cents to airmail a letter that weighed an ounce or less -- much cheaper than at the beginning, for sure, but still three times the regular first-class rate.
Then in 1919 the Post Office discontinued formal airmail service and carried regular first-class mail on planes if space was available. They did this because they were still flying mail planes but with the objective of establishing a transcontinental route.
That was achieved by 1924, and that is when the Post Office re-introduced airmail rates. It charged 8-cents per ounce for each zone or portion of a zone that an item traveled. There were three zones: San Francisco to Cheyenne, Cheyenne to Chicago, and Chicago to New York.
More airmail rates were added in 1925 and 1926. In 1925, a 10-cent rate was introduced for a one-ounce or less letter traveling on an overnight route between Chicago and New York. Then in 1926, the Post Office contracted with private carriers to ferry mail on so-called "Contract Air Mail" or CAM routes that for the most part fed into the government's transcontinental route. There was an entirely separate set of postage rates for mail traveling on CAM routes and for those items that traveled on both CAM routes and the government operated transcontinental route.
This convoluted and complicated system of rates was greatly simplified in early 1927 when a single rate of 10-cents per 1/2 ounce on any route was instituted (i). I'm sure postal customers were elated at this change. Figure 3 shows the air mail map as of late 1927. You can easily see the transcontinental route from San Francisco to New York and the CAM routes feeding into it.
The cover in Figures 1 and 2 was sent from Salt Lake City to New York City via airmail on October 4, 1926, in the middle of this complicated period of airmail rates. It traveled its entire way on the government transcontinental airmail route, so its postage was a straightforward 24-cents, or 8-cents per zone, since it traveled through a portion of the San Francisco to Cheyenne zone and through the entireties of the Cheyenne to Chicago and Chicago to New York zones. The sender paid the 24-cents of postage with two stamps: an 8-cent stamp that is number C4 in the US Scott Catalog and a 16-cent stamp that is number C5.
The cover was postmarked at 3:00 p.m. Mountain Time (5:00 p.m. Eastern Time) on October 4 in Salt Lake City, and it has two New York City circular date stamps on the back, the earlier of the two showing it arrived in the Big Apple by 8:00 p.m. Eastern Time on October 5. It took about 27 hours to travel post office-to-post office, which is consistent with the scheduled flight time of about 25 hours. The item would have flown night and day and made stops in Rock Springs and Cheyenne, Wyoming; North Platte and Omaha, Nebraska; Des Moines and Iowa City, Iowa; Chicago; Bryan and Cleveland, Ohio; and Bellefonte, Pennsylvania (current location of the American Philatelic Society), before landing in New York.
The design of the cover with the red, white and blue stripes was consistent with the postal requirements as of November 1924, as you can see from Figure 4. In May 1926, the Post Office actually changed the order of the stripes to blue, white, and red -- "Since it is the general custom in connection with the arrangement of the national colors to have the blue above the white and red," per the Post Office -- but it did not disallow the use of envelopes printed with the previously approved color scheme.
The cover was sent by "Z.C.M.I. The Peoples Store." ZCMI stood for “Zion’s Co-operative Mercantile Institution,” a department store founded in 1868 by Brigham Young. It was sold to another department store chain in 1999. Macy's now operates out of the ZCMI building in Salt Lake City, retaining the ZCMI initials and the years 1869-1999 in the facade.
I do not have the enclosure, but it was probably business related because the recipient -- Hess, Goldsmith & Co. of New York -- was a textile manufacturer. It was organized in 1885, and by the mid 1950s, it was billed as "America's largest weavers of fine Fiberglass fabrics." In 1956, it was acquired by Burlington Industries and operated as separate unit. It was renamed Burlington Glass Fabrics in 1969, and BGF Industries, Inc. in 1988 when it was acquired by a French company. It remains in business.
This cover was acquired in January 2023 at a Golden Oak Auction for $70.00.
(i) U.S. Domestic Postal Rates, 1872-2011, Third Edition, Henry W. Beecher and Anthony S. Wawrukiewicz, pp. 83-89.
Figure 1 - Front.
Figure 2 - Back.
Figure 3 - Post Office Airmail Map as of November 27, 1927. Source: USPS.
Figure 4 - Excerpt from Postal Bulletin of November 14, 1924.