---
title: "Green and Growing: The World's Largest Wildlife Crossing Nears Its Opening Over the 101"
description: "Native plants are blooming atop the concrete span rising over the 101 Freeway at Liberty Canyon, and the first birds and lizards have already arrived — a milestone that turns the Wallis Annenberg Wildlife Crossing from a construction site into living habitat ahead of its planned December opening."
category: "Los Angeles"
category_url: https://herald.la/category/los-angeles
author: "Gabriela Soto"
published: 2026-06-30T19:48:00.000Z
updated: 2026-06-30T19:48:00.000Z
canonical: https://herald.la/article/green-and-growing-the-worlds-largest-wildlife-crossing-nears-its-opening-over-th
tags: ["wildlife", "environment", "mountain lions", "Santa Monica Mountains", "Agoura Hills", "conservation"]
---
# Green and Growing: The World's Largest Wildlife Crossing Nears Its Opening Over the 101

Native plants are blooming atop the concrete span rising over the 101 Freeway at Liberty Canyon, and the first birds and lizards have already arrived — a milestone that turns the Wallis Annenberg Wildlife Crossing from a construction site into living habitat ahead of its planned December opening.

High above ten lanes of the 101 Freeway in Agoura Hills, a bridge meant for animals has started to turn green.

## From concrete to habitat

Crews have begun planting the top of the Wallis Annenberg Wildlife Crossing, and roughly 6,000 native plants — including California poppies — are now taking root across the span, drawing bees, butterflies and at least one hawk, [the National Wildlife Federation's #SaveLACougars campaign reports](https://savelacougars.org/). The planting marks a turning point: the structure is essentially built, and the work now shifts to growing the soil-and-seed landscape that will make a concrete bridge feel like open ground. A ribbon-cutting is planned for December, [KTLA reported](https://ktla.com/news/california/worlds-largest-wildlife-crossing-nears-next-major-milestone/), with construction having broken ground on Earth Day in 2022.

## Built wide on purpose

Spanning the freeway at Liberty Canyon, the crossing is described by its builders as the largest in the world — about 165 feet wide and 200 feet long, [according to the project](https://101wildlifecrossing.org/). The width is deliberate: a narrow land bridge can read as a trap to a wary mountain lion, so the structure was designed broad enough to feel like a meadow, with a band of restored habitat on either side to guide animals toward it.

## Why it matters here

The 101 has long acted as a wall through the Santa Monica Mountains, hemming in one of the most-studied urban cougar populations on Earth. National Park Service researchers have tracked the cats for more than two decades and documented a grim pattern: animals killed trying to cross the freeway, and a population so genetically isolated that biologists began finding physical signs of inbreeding. Without a corridor reconnecting these mountains to wild lands to the north, scientists have warned, the local mountain lions could eventually disappear. Bobcats, coyotes, deer, foxes and other species are expected to use the crossing too, but the pumas became its symbol.

## P-22's shadow

No animal did more for the project than P-22, the mountain lion who crossed two freeways to reach Griffith Park and lived there, alone, for a decade — becoming a feature of murals, documentaries and the city's imagination before his death in late 2022. The crossing came to carry his story, and his loss helped galvanize the fundraising and political will to finish it.

## Who paid for it

The crossing is named for the philanthropist Wallis Annenberg, whose foundation made an early multimillion-dollar challenge grant that accelerated private giving; the bulk of the funding has come from private donors, with public conservation money making up the rest. The project is a collaboration of the National Wildlife Federation, Caltrans, the National Park Service and other partners. Its cost has risen over the course of construction — pushed up by storm damage and higher material prices — but state funding helped close the gap, and the December target still stands. If it holds, the crossing would open as a rare piece of good news for a region's wildlife: an attempt, as one of its champions has put it, to redeem a freeway by laying a living bridge across it.

## Sources

- [World's largest wildlife crossing nears next major milestone](https://ktla.com/news/california/worlds-largest-wildlife-crossing-nears-next-major-milestone/)
- [#SaveLACougars — National Wildlife Federation](https://savelacougars.org/)
- [Wallis Annenberg Wildlife Crossing — project overview](https://101wildlifecrossing.org/)