Representations of large-scale spaces by grid cells in the medial entorhinal cortex (mEC) requires uniform firing patterns throughout the space being navigated. However, boundaries can disrupt grid-cell firing patterns, suggesting an influence of local environmental cues. Recordings from mEC neurons in a two-compartment chamber showed that, although mEC-cell firing was initially influenced by local cues, firing patterns subesquently formed a single, continuous grid representation that spanned both compartments. Thus, grid cells can uniformly cover the space to be navigated and support large-scale spatial navigation.