Seattle flies the blue “12” flag as a symbol of the Seattle Seahawks’ fans, who are known as the 12s (formerly the “12th Man”), representing the fans as the extra, 12th player on the field.

What the 12 flag means

  • The number 12 stands for the fans, imagined as an extra player who helps the team through crowd noise and energy.
  • Seattle is famous for loud home games; the stadium was even engineered to trap and amplify noise, reinforcing the idea that fans are part of the action.
  • The flag is a visible way to show that city and fans are “on the field” with the team, especially during big games and playoff runs.

How the 12 flag tradition started

  • In 2003, the Seahawks formally honored their fanbase with a dedicated “12” flag at the stadium.
  • The first official flag-raising happened on October 12, 2003, when 12 original season-ticket holders hoisted the flag before kickoff.
  • Since then, local celebrities, veterans, athletes, and community figures are invited to raise the flag before home games as a pregame ritual.

Why you see 12 flags all over Seattle

  • During playoff pushes or season openers, people and businesses across the city fly the 12 flag from buildings, houses, and even landmarks like the Space Needle.
  • Large roadside or hillside 12 flags (like the massive one visible from I‑90 near Issaquah) are fan-made tributes that have become local landmarks in their own right.
  • The flag has become part civic symbol, part sports banner—when it’s up everywhere, it’s a signal that Seattle is in full Seahawks mode.

Meta description (for SEO)

Seattle’s “12” flag honors the Seahawks’ fanbase, the 12s, symbolizing them as the team’s extra player. Learn why Seattle flies the 12 flag, its origins, and how it became a citywide tradition.

TL;DR: Seattle has a 12 flag because the Seahawks’ fans are called the 12s, treated as an honorary 12th player whose noise and passion are so important that the team created a flag and pregame-raising ritual to celebrate them.

Information gathered from public forums or data available on the internet and portrayed here.