Why do European books have the words on the spine the opposite way around?

On American published books, when the books are face up in a pile, you can read the spines. European books read correctly only if the book is face down. Why the difference?

The tradition to write on the spine top-to-bottom is older; its roots can be traced back to the time when books were few. The reasoning was that if a book is lying on the table (or in a small stack) face-up, reading its title should be easy.

The tradition to write on the spine bottom-to-top is younger; it’s more concerned with how easy it is for the bookshelf owner to handle the book. Reading bottom-to-top is easier, because this direction is more in keeping with the European left-to-right writing tradition, which is especially apparent when there are several lines of text on the spine (an urge to read the lines left-to-right is only natural).

The Western Europe and the US opted for the more venerable tradition, while the Eastern Europe and Russia aligned themselves with the more modern one. What the reader should remember is that both traditions are centuries old.

Bookbinding: Spine titling

In languages written horizontally, conventions differ about the direction in which the title on the spine is rotated:

• In the United States, the Commonwealth, Scandinavia and for books in Dutch, titles are usually written top-to-bottom on the spine. This means that when the book is placed on a table with the front cover upwards, the title is correctly oriented left-to-right on the spine. This practice is reflected in the industry standards ANSI/NISO Z39.41 and ISO 6357.
• In most of continental Europe and Latin America, titles are conventionally printed bottom-to-top on the spine so, when the books are placed vertically on shelves, the title can be read by tilting the head to the left.