Meridian 88 walks in a straight line. This is the defining and most unnerving characteristic of a machine that has been doing nothing but walking north-south along the 88th meridian west — longitude 88°W — for as long as anyone has documented the Behemoths. Its path follows the line to within two meters of precision. Not magnetic north, not grid north, but true geodetic north, as if it is calibrated to the planet's rotational axis. The 88th meridian cuts through western Indiana and eastern Illinois, passing roughly 40 kilometers west of downtown Chicago. Meridian 88 walks between the Wisconsin-Illinois border near Beloit and the drowned floodplains where the Wabash meets the Ohio in southern Illinois — a corridor of roughly 500 kilometers. The cycle takes approximately four months. South to the river. North to the border. Turn around. Repeat.

The 88th meridian passes close to the GLMZ but Meridian 88 has never entered the metropolitan zone. Many residents consider it a guardian angel — a silent sentinel pacing the western approach — though machine-behavior researchers insist it is simply following its meridian line with the same mechanical indifference as every other Behemoth. The fact that it happens to pace a line just west of the last functioning megalopolis is, they assure us, coincidence. Not everyone is assured.

Meridian 88 is bipedal — the only Behemoth that walks on two legs. It stands fifteen stories tall and has a roughly humanoid silhouette, which makes it the most psychologically disturbing of the Behemoths to encounter. Its 'head' is a featureless dome of sensor equipment that rotates slowly and continuously, scanning the horizon. Its 'arms' hang at its sides, swinging with its stride, and they end in complex manipulator clusters that have never been observed doing anything. The machine walks with a steady, mechanical rhythm that never varies — one step every 4.2 seconds, day and night, rain or shine, year after year.

The mystery of Meridian 88 is its purpose. It doesn't harvest. It doesn't build. It doesn't manufacture. It doesn't collect. It just walks, measuring something with every step. Seismologists have noted that its footfalls generate precise, regular vibrations that penetrate deep into the earth — and that these vibrations are measurably different from random impacts. Some believe Meridian 88 is conducting a geological survey. Others think it is a timing mechanism — a pendulum. A few suggest it is a message, written in footsteps on the skin of the earth, for a recipient that hasn't arrived yet.