"Four decades have passed since the first trans-oceanic supersonic passenger flight took off from London Heathrow Airport in 1976. Subsequently, more than 2.5 million passengers flew supersonically until British Airways and Air France took the Concorde out of service in 2003. Although no supersonic passenger aircraft have flown since then, aviation enthusiasts, aircraft and parts manufacturers, airlines, and some Members of Congress have expressed interest in restarting supersonic air travel. Several U.S. startup companies are now developing supersonic commercial and business jets. The major issues affecting the introduction of supersonic aircraft appear to remain the same as in the Concorde era--how to translate technological advances into commercial ventures that are economically viable and acceptable to regulators and the public. Gaining international consensus and approvals to fly supersonically over other countries besides the United States may be a critical element in determining the market viability of future civil supersonic aircraft designs. International agreements would also need to address permissible conditions for supersonic flight operations over water and over polar regions that have opened up to civil aircraft operations over the past decade and offer shorter flights between the United States and Asia."
CRS Report for Congress, R45404
Congressional Research Service: https://crsreports.congress.gov/