I will speak to the Inland Northwest because that is where I have had my Huckleberry picking experience. You will have to head to the mountains and scout locations starting in early July to see how things are ripening up. Good luck in getting an answer from locals as to where to pick them. Usually, this is a secret kept in the family for years. It is almost like asking them where their claim is after seeing a huge nugget of gold pulled out of their pockets. I recommend stopping by the local US Forest Service or Department of Fish and Game. One of them should carry local mountain road maps. This will help you in the even you get lost. You can’t always get cell service in the mountains. I have started on mountain roads near the western border of the Idaho panhandle and ended up in Montana near the Canadian border taking nothing but mountain roads. The map, along with a full tank of gas, will come in handy.
You will be heading up roads that were designed for logging. They will be narrow and some not well maintained or used. As you head of into the mountains, start looking for the plants along the roadside. They may not be heavy with fruit but will tell you if you are getting to the right elevation. The leaves have been described as leathery in texture with a slight serration to the leave edges that will be about an inch to inch and a half long. The bark is smooth and stems are thin. In the spring, they will produce pink bell shaped flowers.
Unlike the blueberry that usually grown in clusters, the huckleberry fruit is usually spread more apart on the plant. As the fruit reaches its peak in ripeness and the summer months get warmer, the leaves can sometimes have a reddish tint to them.