A look at why teen takeovers — large unruly youth gatherings — are spreading, framed as a warning sign about decaying communities.

• Teen takeovers are growing because the safe spaces kids once had are gone.
• Parks, rec centers, and YMCAs got wrecked by older residents over the years.
• With nowhere to go, bored teens end up causing trouble in groups.
• The decline is recent — not the 1950s or 70s, but the 2000s and 2010s.

Outlook: Without new outlets for young people, these takeovers are likely to keep spreading.