X-line routing arrangements for dense multi-chip-package interconnects are described. In an example, an electronic signal routing structure includes a substrate. A plurality of layers of conductive traces is disposed above the substrate. A first pair of ground traces is disposed in a first of the plurality of layers of conductive traces. A signal trace is disposed in a second of the plurality of layers of conductive traces, below the first layer. A second pair of ground traces is disposed in a third of the plurality of layers of conductive traces, below the first layer. The first and second pairs of ground traces and the signal trace provide an X-pattern routing from a cross-sectional perspective.