In episode 93, we get curious about subways for Sam of Toronto, Ontario.  Why do we need subways?  How are subway tunnels built?  Which is the busiest subway system in the world?  Learn all about it in this week's super-interesting transportation episode.  Send Us An E-mail - [email protected] Us A Voicemail - 856-425-2324Support Us On Patreon - https://www.patreon.com/CuriouskidpodcastShop Curious Kid Podcast Merchandise - http://tee.pub/lic/fqXchg3wUVUFollow Us On Facebook - https://www.facebook.com/curiouskidpod/Follow Us On Instagram - https://www.instagram.com/curiouskidpodcast/Follow Us On Twitter - https://twitter.com/CuriousKidPod