In the southwestern US, rainfall amount and climate have varied in response to glacial cycles over the past several hundred thousand years. Lake sediments can preserve climate history and here, we use two large lakes in Utah, Great Salt Lake and Bear Lake, to study how the region’s rainfall has changed over the last 240,000 years. We measure wax molecules from plant leaves that blew into the lakes and then were preserved in lake sediments. These molecules record rainfall history across two large climate swings associated with the last two glacial cycles. We compare archives between a salty lake that has historically fluctuated between a massive, deep, fresh state and a small, shallow, hypersaline state, and a smaller, fresher lake located at higher elevations. We find that rainfall changes at the two lakes happened at the same time and corresponded to the ends of glacials. Studying how mid-continental rainfall patterns changed in the past helps us understand the stability and variability of our climate between glacial and interglacial times.