You can apply visa with your american passport. Please refer the below information.
1. Online application form http://www.rree.gob.bo/formvisas/
2. Valid passport (at least 6 months left and has available page) and a copy.
3. Yellow fever certification and a copy
(In case you plan to visit only UYUNI and LA PAZ, it's not required)
4. Reservation of accomodation.
5. Bank account statement original more than 500 dolors in English.
6. In and out flying ticket (from and to bolivia or from and to Latin America)
7. 1 foto with passport size, within 6 months, with white backgroud.
8. Deposit of 160 US Dollars per each document. (Original and translation)
Account Name : EMBAJADA DE BOLIVIA(CONSULADO)
Account No. : 650-009825-350
Bank Name : KEB Bank
Bank Address : 66, Eulji-ro, Jung-gu, Seoul, Republic of Korea
Swift Code : KOEXKRSE
(The commission fee should be discounted from the sending bank account and not from the amount sent.)