Archive? Library? What's the difference?
Archives and special collections departments of libraries usually have very specific policies regarding access to and use of their collections. Many archives are available by appointment only. Some archives will allow users to photocopy materials or use digital cameras, others will not. These policies are intended to safeguard the materials in their care in order to make these materials accessible to you and to future generations of researchers.
Archives and special collections try to balance providing access to their collections with the preservation of their materials. It is generally a good idea to contact the archivist in advance to make arrangements before you visit.