The Market Revolution - Transportation & Communication (Khan)
The link address is: https://www.khanacademy.org/humanities/ap-us-history/period-4/apush-politics-society-early-19th-c/v/the-market-revolution-part-2
The link address is: https://www.khanacademy.org/humanities/ap-us-history/period-4/apush-politics-society-early-19th-c/v/the-market-revolution-part-2