The World's fair began in the mid-19th century as a way to showcase the latest advances in technology and give the public a glimpse into what the world may look like for future generations. The location of the fair has moved each year to a different host city and has now been held in cities all over the world. Each fair has had its own poster to promote the event and the artistic style and imagery has evolved to be representative of the era and location of the fair. My favorite time period for World's Fair posters spans the early to mid-20th century and I've selected four of my favorites to showcase here.