Abstract: With almost 100 gravitational-wave sources detected to-date, and the first-generation facilities now over 20-years old, there is growing momentum towards the next-generation of gravitational-wave observatories. Projects are underway in Europe, Australia, Japan, India and the US to bring new ground-based observatories online. These audio-band observatories will be complemented by a wide range of efforts targeting other gravitational-wave frequency-bands. In this talk, I will focus on the US effort to build a next-generation observatory, known as Cosmic Explorer.