From the promoters of the State Line Road Race:

Registration closes at 11:59PM CDT next Wednesday night (July 17th). There is no registration the day of the race. Last year most of the people registered within the week prior to the race and we expect the same thing will happen this year. Also, last year the category 5 race maxed out at 50 riders and some category 5 riders were put on a waiting list (and not able to race). So if you are a category 5 and want to ensure that you have a spot I would recommend that you do not wait until Wednesday to register. 

Photo Credit: Roger Harrison