The direct measurement of gravitational waves is a powerful tool for surveying the population of black holes across the universe. From LIGO, we have already found some of the heaviest black holes that can be formed from stars. Recent pictures have further confirmed the super-massive black holes at the centers of the galaxy. However, there exists no unambiguous evidence to date of black holes in the intermediate-mass range between stellar and galactic limits, hinting at a possible mass-gap in our universe. In this talk, I will show results from LIGO's ongoing search for intermediate-mass black holes and the implications these sources hold for the next 20 years of gravitational-wave astronomy.