I have a box of old post cards from about 1900-1915, most of them with a short message on the address side and the back side a color illustration. In those days there were several trains each way every day carrying mail. Family members in small towns or in the country usually didn't have telephones, so they used the post cards to communicate, and the cards probably got delivered the next day.
We lived in the country and ordered all kinds of clothing and small household items by mail from Sears Roebuck in Ft Worth, TX, paid for by postal money orders bought from the RFD carrier with cash in the mail box.
Life was good (and inexpensive too).