Milner Pass is where Trail Ridge Road crosses the Continental Divide, at 3,279 metres, and it does it so quietly that you could miss it. There is a modest sign, a small parking area, and a little tarn called Poudre Lake lying right beside the road. Rain that lands on the east side of the sign heads for the Cache la Poudre and eventually the Platte; rain on the west side ends up in the Colorado. Standing there in a riding jacket, still ringing from the climb, it feels like a very large idea for a very small place.
The riding on either side is the reason you came. From the east you have already done the big work above the treeline, with the tundra running off in every direction and the road cut into the slope with a low stone wall as the only comfort. Milner sits just below that, back among spruce and fir, so the character changes: tighter, shadier, and often a few degrees colder than you expected. Heading west the road drops toward the Kawuneeche Valley, where the infant Colorado River winds through meadows that are a good bet for elk at dawn and dusk. Look across to the Never Summer Mountains and you can see a long pale scar along the slope. That is the Grand Ditch, dug by hand and horse in the late nineteenth century to carry headwater snowmelt over the divide to farmland on the plains.
Plan around the season. Trail Ridge Road closes with the first serious snow, usually somewhere in October, and does not reopen until late May, after crews have carved a canyon through drifts that can be several metres deep. In between, the pattern is reliable: clear mornings, building cloud by noon, thunder in the afternoon. Be over the top before lunch if you can. It is cold up here even in July, so keep a warmer layer in the bag, and remember the park charges an entrance fee and can limit entry at busy times.
Nothing here sells petrol. Estes Park, about 25 kilometres east, is the sensible place to fill the tank before you climb, and on the west side Grand Lake and Granby are your options on the way down. Fill up before the park, because the pass itself is all scenery and a few picnic tables, and the pit toilets at the pull-out are about as luxurious as it gets.