We use a systematic literature review methodology to answer the following questions pertaining to smart cities and blockchain: (i) Why was blockchain chosen as the solution? (ii) What blockchains are being considered for use in smart cities and why? and (iii) What blockchain based applications are being researched for smart cities? Our results - based on 45 peer-reviewed academic studies all published in journals that met pre-defined search criteria - show that increased security, privacy, and trust are the reasons most cited in the literature for the use of blockchain for smart cities. Consortium, Hybrid, Private, and Public blockchains are discussed with respect to their suitability for smart cities applications, and finally, we discuss smart cities blockchain applications from the literature using a taxonomy based on the framework defined by Silva et al. . In conclusion, this study highlights the current blockchain challenges and future research opportunities, including the need to change the current mindset of centralized control and trusted third parties to a more participative engagement model across smart cities.