The Closed Trail Almanac

Boulder OSMP posts trail closures on one page and deletes them once they lift. Nobody keeps the history, so nobody can answer how long a trail was actually shut. This is that record, and it's now running daily.

Covering 19 July 2021 to 26 July 2026. Figures generated 26 July 2026.

The part that changed the project

The plan said start the scraper and wait a year before there's anything worth publishing. That turned out to be wrong. The Internet Archive had quietly been capturing this page since 2021, and it holds 46 usable snapshots. So instead of launching with nothing, the almanac launched with five years of history already in it. The daily job just makes it denser from here.

That's the difference between an asset that's useful next summer and one you can pitch this month. Everything below already exists.

What's been closed the longest

Ranked by how long the closure has been observed, not by how long it was announced for.

Three stories already sitting in the data

A closure nobody has mentioned in five years

The Boulder Star area on Flagstaff Mountain has been closed continuously for at least 1,833 days, and the true figure is longer, because it was already in place the first time the page was archived. The original notice is dated October 2020 and describes replacing temporary fencing with reinforced wood fencing. That's a five-and-a-half-year "temporary" closure that has never been revisited publicly.

OSMP quietly split its raptor categories

In 2021 the page listed one "Cliff-Nesting Raptor Closures, Feb 1 to Jul 31." By 2026 that had become two separate entries, "Golden Eagle Closures, Dec 15 to Jul 31" and "Falcon Closures, Feb 1 to Jul 31." The golden eagle window moved about seven weeks earlier in the process. Anyone planning a winter climbing season off the old dates would now be wrong, and the change was never announced anywhere that persists.

Construction is the quiet majority

Of the 89 closures on record, 28 are trail work or construction and only 13 are wildlife. The public conversation about Boulder trail closures is almost entirely about raptors. The record says the thing most likely to shut a trail is a crew with equipment.

How this can mislead you, in the reporter's words

Every figure above is a floor, not a measurement, and the dataset says so in four places. Anyone quoting it should read these first.

What makes it hard to copy

The archive stores raw HTML before parsing anything, and the parser rebuilds the whole record from scratch on every run. That means a parser fix applies retroactively across all five years instead of forcing a rewrite. It already mattered twice: the city changed its heading structure between 2021 and 2026, and it lists closures in two different formats depending on the era. Both would have silently destroyed a parser that only kept its own output.

The moat isn't the code, it's the elapsed time. Anyone can write this scraper. Nobody else can go back and watch 2022.

What happens next

Build a /trail-closures/ page on boulderthingstodo.com and publish the dataset as a download, because publishing the raw data roughly doubles citations. Pitch climbing and outdoor press through the eight-tier outreach list that's already on the link-earning program page. Don't build a second outreach list.

After that it earns links passively. Every time OSMP announces a closure, this is the only place that can say how unusual it is.

Data generated 26 July 2026 from 47 archived captures. Scraping is permitted: the city's robots.txt carries 127 rules and none cover this path, verified directly. Regenerate the figures any time with parse.py.