Footwear systems include an article of footwear and a data transmission system engaged with the article of footwear. The transmission system transmits data to a remote system, such as a display system, another data transmission system, a processing system, etc. Such footwear systems further may include activation systems for activating the transmission and/or display systems. The transmitted data may be used for various purposes, such as: (a) identifying a user of the article of footwear; (b) activating targeted advertising or product information; (c) confirming the user's presence at a specific location and/or at a specific time; (d) determining start, finish, and/or intermediate split times for specific user; (e) confirming athletic equipment usage; (f) providing data for a game or reward program; (g) registering the user for an event or competition; or the like.