The proliferation of new shared-ride transportation services provides a unique opportunity for transit agencies to reach new markets. Unfortunately, many transit agencies are wary of partnering with private companies. To address these concerns, this research analyzes the usage data from a unique joint carsharing\transit smartcard in Chicago. This work explores the general revenue and ridership impacts of this smartcard before examining the impact of a promotional incentive of a $50 transit credit. The research found that the joint smartcard steadily increased transit ridership and revenue. The research also found that the promotion attracted new cardholders who were more likely to reduce their public transportation use and spending than a non-incentivized group; however, the large numbers attracted by the promotion meant that on aggregate, a year later, the incentivized group still spent more than three times as much on transit as the non-incentivized control group. These findings suggest that strategic partnerships and financial incentives are successful ways to market transit. Furthermore, joint carsharing\transit smartcards represent a specific partnership with a high probability of success.