The US replaced organ-allocation maps with one continuous score across the country.

Because organ allocation was carved into donation service areas and regions, a patient's access to a transplant could turn on where they happened to be listed, which is exactly what the federal Final Rule was written to forbid.

UNOS's continuous-distribution approach replaces those hard areas with a composite allocation score: all candidates are ranked nationwide by a weighted sum of medical, match and efficiency factors, then the organ is offered by that score.

The framework is built attribute by attribute, with the weights set through structured stakeholder exercises that compare each factor against the others, and proximity points are retained only to limit how far a viable organ has to travel.