ZnO nanowires have recently been used as the electron transport material in a variety of optoelectronic applications such as transistors and dye sensitized solar cells (DSSCs). Such applications will benefit from knowledge of the fundamental electron transport properties of the semiconductor nanostructures. In this paper, we investigate the time-dependent photoconductivity of ZnO nanowires over sub-picosecond to nanosecond time scales using time-resolved terahertz spectroscopy (TRTS), and we compare the nanowire photoconductivity to that of ZnO nanoparticle films, polycrystalline thin films, and bulk ZnO. TRTS allows the extraction of the frequency-dependent complex conductivity using a non-contact optical probe. TRTS is ideal for probing photoexcited electrons because scattering rates are typically in the 1-10 THz regime. ZnO nanowires were grown in dense vertical arrays by chemical bath deposition. Nanowires grow in the [0001] direction with hexagonally faceted sides due to ZnO's wurtzite crystal structure. We have grown nanowires up to 8 μm long with diameters under 200 nm. Absorption of a near-UV photoexcitation pulse by the ZnO generates electrons in the conduction band. These photoexcited electrons absorb THz radiation, forming the basis of our THz pump-probe studies. Electron injection occurs on sub-picosecond time scales and the photoconductivity decays slowly over nanosecond time scales. Nanowire photoconductivity retains 80% of its initial value after 800 ps, while photoconductivity of the nanoparticle film decreases to about 50%. The ZnO polycrystalline film photoconductivity decays the slowest, retaining 95% of its original photoconductivity after 800 ps. Photoconductivity decreases as mobile electrons in the conduction band become trapped or recombine at defect sites or surfaces. The relative decay times of these three morphologies indicates that much of the recombination is occurring at surfaces and grain boundaries. Frequency-dependent photoconductivity calculated from the transmitted THz field through photoexcited and non-photoexcited nanowires is conclusively non-Drude. Materials which follow the Drude model have non-zero real DC conductivity that decreases to zero at higher frequencies. The real photoconductivity in these ZnO materials increases with increasing frequency. Furthermore, the imaginary part of the conductivity is negative, which is impossible according to the Drude model. This is often the case for nanomaterials and can be explained either by backscattering of electrons at grain boundaries or by effective medium theory. The real DC conductivity is significantly larger in nanowires than in nanoparticle films. This increased real DC conductivity along with the relative decay times of the photoconductivity indicate that nanowires could provide improved electron transport over nanoparticle films in DSSCs and other devices that require fast electron extraction from a bicontinuous heterojunction structure.