Across much of the world, access to electricity is uneven and shaped by complex political considerations. While the electricity access gap is well recognized, reliable data remains scarce on the spatial extent of the power grid and how the benefits of electricity are distributed across much of the world. We introduce the first large-scale effort to systematically track the expansion of rural electricity access in a country using the complete historical archive of nighttime satellite imagery over a two-decade timespan. Drawing on all imagery captured over 8,000 nights, we extract the observed visible band brightness over every village point in India. We introduce a statistically recalibrated measure of brightness that better discerns changes in ground-based light output from other sources of atmospheric and image noise. To demonstrate the utility of this approach, we conduct a geospatial evaluation of a large village electrification program launched in 2005 across India. Using interrupted time series analysis methods, our results show wide variation in the effectiveness of electrification projects, and significant geographic clustering of impact trends across the country that are at least in part explained by electoral considerations.