Nanoscale materials based on the element carbon have attracted tremendous attention over the years from a diverse array of scientific disciplines. There is particular interest in the development of such materials for electronic device applications, thus requiring comprehensive studies of their electrical transport properties. However, in systems with reduced dimensionality, the electrical behavior may show significant variation depending on the local physical structure. Therefore, it would be most ideal to understand these two facets simultaneously. In this thesis, we study electrical transport in carbon nanotubes, pentacene thin films, and graphene in a spatially resolved manner in combination with two different microscopy techniques. With photoelectrical microscopy, we first image the electrical conductance and transport barriers for individual carbon nanotubes. We then resolve the precise points where charge injection takes place in pentacene thin-film transistors and explicitly determine the resistance for each point contact using the same technique. Finally, we study the polycrystalline structure of large-area graphene films with transmission electron microscopy and measure the electrical properties of individual grain boundaries.