Kings Crossing, a proposed development hoped to be the flagship of revitalization efforts on Route 1 in Fairfax County, has been scuttled amid a sour economic climate that made the project far less lucrative than when developer JPI proposed it.

In a letter this week to community leaders and Fairfax County officials, JPI Senior Vice President Aaron Liebert said the long-awaited town center wouldn’t move forward “after more than four years of hard work and significant expense,” spelling out a major setback in a broader campaign to rejuvenate the stretch of south-county highway.