  We take a comprehensive look at conductors used in superconducting magnets
for the accelerator sector and explore the ramifications of the present
marketplace for supply of conductor to future accelerator facilities. While
there are thousands of superconductors, many of which have promising properties
for applications, we outline the journey a promising material must take to
become a magnet conductor that is manufactured at the scale needed for an
accelerator facility. Among the few materials that actually reach this scale,
Nb$_{3}$Sn is arguably the workhorse conductor for the next generation of
accelerators. Yet, a marketplace pull equivalent to the medical imaging magnet
industry, which consumes close to 1000 tons of commodity-scale Nb-Ti conductor
per year, has not emerged. This aspect greatly complicates the steps that must
be taken to assure readiness of manufacturing for the next accelerator
facility. Meanwhile, high-temperature superconductors (HTS), which are capable
of extremely high fields at low temperature, are advancing rapidly as magnet
conductors, and the long horizons of large physics projects could provide time
for them to emerge and displace Nb-based materials. We close by examining in
more detail the ecosystem that connects accelerator magnet conductors with
broader industry applications, in particular areas that are presently in rapid
development such as fusion and wind turbines and which would potentially
require hundreds of tons of conductor.
