From Quito, buses will drop you at the bus terminal if Latacunga is their final destination. If the bus is continuing to Ambato or Riobamba, it’ll drop you on the corner of Avenida 5 de Junio and Cotopaxi, about five blocks west of the Panamericana and 10 minutes’ walk to downtown. Some, however, will just drop you at the Panamericana, where you can catch a taxi ($1 to $1.50).
Buses to Quito ($2.15, two hours) and Ambato ($1.15, one hour) leave from the bus terminal and from the corner of Avenida 5 de Junio and Cotopaxi. For Riobamba, it’s easiest to catch a passing southbound Cuenca bus from the corner.
You can hire taxis and pickup trucks in Plaza Chile (also called Plaza El Salto) for visits to Parque Nacional Cotopaxi (park interior $30, Control Caspi entrance $20).