The Library of Congress has many reading rooms for researchers to access the plethora of materials in the collections. The Newspaper and Current Periodicals Reading Room is inside the Madison building, one of three LOC buildings on Capitol Hill in Washington, DC.
I have not yet found the time to visit this reading room, but hope to eventually. For those not able to make a trip in person, some resources are available online through the division's work with national programs such as the National Digital Newspaper Program, some webcasts about the collection, search tools, and a bibliography of Internet resources outside of the Library of Congress. The bulk of the collection is only available inside the reading room, however some duplication services may be available for off site patrons, for a fee.
The Comic Book Collection at LOC is probably one of the largest in the United States. Full access to the fragile materials is limited to serious researchers, but there are an extensive number of titles available in the Comic Book Fiche collection which can be photocopied following the general photocopy guidelines. For some instant gratification, and fun times also check out the digitization project at University of Nebraska - Lincoln Libraries, Government Comics Collection. These two covers, taken as screenshots from the digital copy online link to the full online version. These are just two of the many gems worth browsing through in the University of Nebraska Libraries digital collections.