Characterization of the binary supermassive black hole (SMBH) population across cosmic history is a critical pathway to understanding galaxy/SMBH assembly and forecasting low-frequency gravitational wave detection in the coming decades. Following the merger of two galaxies, the two SMBHs within each of the galaxies will pair and eventually evolve into a bound binary, separated by a few parsec, via dynamical friction with stars and other dynamical processes. Studying SMBH pairs at different evolutionary stages, e.g., from tens of kpc separations at the beginning of the galaxy merger to ~10 parsec scales of bound binaries, provides the foundation to understanding AGN fueling and the dynamical evolution of SMBH pairs in mergers. In this talk, I will review our current understanding of SMBH pair evolution in galaxy mergers, and present our observational efforts of identifying galactic-scale SMBH pairs at cosmic noon (z~2). I will highlight the importance of multi-wavelength observations on constraining the statistics of these objects as well as their physical properties, with an outlook for upcoming space-based wide-area imaging/spectroscopic surveys.