How SOSUS evolved into a North Atlantic surveillance network

How did SOSUS upgrades affect its ability to detect submarines during the Cold War?

The network matured over decades, and early segmented coverage and limited cross-station data sharing left seams that later relay and integration improvements reduced.

SOSUS developed over decades rather than appearing as a single finished invention. Its initial installations date to the 1950s, major maturation followed in the 1970s, and further data-relay improvements arrived during the 1980s. Earlier coverage was divided among stations, so information had to be passed between separate operating areas. A submarine exploiting the boundary between those areas could turn an organizational seam into an evasion route.