Washington DC's special Lobbying business doesn't accumulate cash itself. Instead, it activates a city-wide revenue boost on another board:

• When you first build the Lobbying business, you choose which other city it lobbies for (NYC, SF, Palm Beach, Dallas, or Vegas). This city is locked in until you sell the business.
• Landing on a completed Lobbying business triggers a 10-minute revenue boost on a business in the chosen city. The boost size depends on the lobbying level: L1 = 1.2x, L2 = 1.5x, L4 = 2x.
• Landing again while a boost is active extends it by 10 more minutes.
• Landing after a boost expires starts a new boost on the next business in that city, cycling 1 → 2 → 3 → 4 → 5 → 6 → 1.

The lobbying boost stacks with other revenue buffs (event multipliers, prestige NFT bonuses, etc.).