Possible Clues:

• $200 Monopoly acquisitions: Abbr
• The 1906 Hepburn Act gave the ICC power to set rates for them
• Monopoly game's B&O and Reading: Abbr
• B&O and others (Abbr.)
• The B&O et al
• Lines on some maps: Abbr
• Board game spots with nine sqs. between them
• Jay Gould concerns, briefly
• B&O and others: Abbr
• Track lines: Abbr