Spearfish Canyon is actually located northwest of Deadwood, while Custer is located southeast of Deadwood. We would definitely encourage you to make a trip through Spearfish Canyon during your stay, however the direct route to Custer would not take you through the Canyon. For more information on Spearfish Canyon, we would invite you to check out our website: www.visitspearfish.com. There is plenty of information on the Canyon, Fall Foliage, Hiking, and other outdoor activities. If you have any other questions, feel free to contact us at email@example.com.
Have a great trip!