Entry No. 60 — the Seattle file — filed under: ruins

Abandoned Clay Pit

Located within Cougar Mountain Regional Wildland Park, this massive open-cut mine was operated by Mutual Materials from the late 1950s until the 2008 recession. It supplied raw clay to the Newcastle brick plant, producing the bricks used to build the University of Washington's Red Square and T-Mobile Park. Today, the pit has been graded and seeded as a meadow, leaving a vast, red-tinted clay depression surrounded by regrowing forest.

The move: Hike along the wide, gravel Clay Pit Road from the Sky Country Trailhead to the overlook at the edge of the pit, where you can enjoy views of the red clay landscape and Tiger Mountain.

📍 Before you go While the Clay Pit Road trail leads directly to the edge of the pit, the actual floor of the clay pit is a protected habitat restoration area and is marked as 'no public access' on park maps.

• 📍 Renton
• 💸 Free
• ⚡ Low-key
• 🌗 Outdoors

Where: Renton, WA 98059, USA

Hours: Added 2026-07-20 — confirm current access before you go.

Plan a visit & invite your people →

Further reading: Wikipedia · rentonreporter.com

last checked: 2026-07-20