The cigar box guitar was created from a mix of slavery, musical expression, poverty and whatever materials were to hand. African slaves shipped to the United States to work the plantations, came with nothing but their musical traditions. It is difficult to image how hard life was for slaves in the US. They lived in poverty as chattels, owned by masters who were often brutal and cruel. Musical activity was repressed by the white slave owners as they feared its power - so with no ready access to instruments, inventive ways were found to make them from whatever was available.
In the mid-1800s, cigars were shipped in boxes containing 20-50 cigars. The boxes were usually made from cedar which has a particular resonating quality ideal for acoustic sounds.
A broom could be taken apart, the wire holding the brush removed and stretched along the broom handle that was fixed into a discarded cigar box. With no frets and a very high "action" it was best played with a slide made from the top of a glass bottle or piece of pipe and the birthing cry of the blues was heard. Another adaption was into a fiddle type instrument that could be bowed. This version was often called the Diddley Bow. A larger bass could be constructed using a tea chest as the soundbox.
The cigar box guitar was expanded, more strings added and from these basic instruments came what we now see as the foundation of blues and its renegade child called rock 'n roll.
In the depression years, when poverty and hardship put manufactured instruments beyond the means of many people, the need to make music and sing created a new reason to create these simple handmade instruments.