Color isn't important. What is important is the letter shown for the campsite on the Availability tab.
Looking at Fort Pickens for April, I see the letter R for almost every campsite for the entire month of April. Which means someone has that campsite reserved for that day. Every day in April.
There are about 15 sites with the letter X which means that site cannot be used, usually a problem such as a broken electrical pedestal, or erosion, or such.
If the sites were available for walk-ins they would have the letter W on the Availability tab
Full-Time 2014 - ????
โNot all who wander are lost.โ
"You were supposed to turn back at the last street."
2012 Ram 2500 Mega Cab
2014 Flagstaff 832IKBS TT