Related Clues:

• 5K, say
• Indy 500, e.g.
• Iditarod, for one
• Where 'They're off!' may be heard
• Sprint, for one
• Sprint or dash
• Marathon or 10K
• Sell quickly
• Unscientific human grouping
• Pre-election activity
• Daytona event
• Senate contest
• Census form info
• Steeplechase, e.g.
• Cross-country event