What happens to cotton when it is harvested?

The cotton is picked with a cotton picker machine and put into big cotton trailers. After the field is picked (it takes 3-4 runs through the field to get all the cotton off the bolls) the trailers are hooked up to trucks and the raw cotton is taken to the gin. At the gin the trailers are put under a big vacuum that sucks up the raw, dirty cotton. The cotton is cleaned, seeds removed, and stems, leaves taken out. It is then packed into big bales and stacked up.