Mrs. May B. May lived in Carnegie, a borough in Allegheny County that is now part of the Pittsburgh Metropolitan area.
In the early twentieth century, Carnegie was an important center of coal mining and steel production, and was connected to area and national rail lines.
https://en.wikipedia.org/wiki/Carnegie,_Pennsylvania
In February of 1914, Mrs. May received a postcard Valentine from Lizzie.
The postcard was not mailed, suggesting that Lizzie lived nearby – perhaps a neighbor, friend, or relative.
The face of the postcard is an interesting drawing by the celebrated postcard artist and publisher, John Winsch.
Winsch copyrighted the design in 1913.
Interestingly, Winsch has no Wiki entry in English; here is the German language entry in translation.
Upon a map of the United States, Winsch illustrates the sending of a telegram in two medallion drawings.
In the first medallion, (which would appear near the State of Ohio), a customer presents a message at the counter of a Telegraph Office.
A jagged line, suggesting electricity, delineates the message, “To My Valentine”.
The second medallion (which appears on the map in the southwest US) shows a uniformed delivery boy handing a telegram to a woman outside her house.
A pair of lovebirds appear in the margin on the right.
On the reverse, we learn that Mrs. May has recently moved.
Lizzie writes, “Here comes the 1st card from me to your new home.”
Lizzie expresses a hope that May “will enjoy it as well” – presumably, both the postcard and the new home.
Mrs. May preserved the Valentine in good condition throughout her life.
One hoes that Lizzie and May maintained a friendly correspondence for many years.
