Qualifications
Many urban planning gigs require a master's degree in the subject, which will teach you crucial skills, such as mapping, project management, design software, professional ethics, and fostering an air of superiority. You'd better be good with computers, too. You'll need to be great with spreadsheets and programs like AUTOCAD, Adobe, and geographic information systems (GIS) (source).
Yes, there are some things your smartphone can't do. Some employers will accept work experience alone, or a mixture of experience and education, but usually a degree is your key to enter.
Some employers require accreditation by a professional organization like the American Institute of Certified Planners (AICP), which involves passing an exam and completing ongoing education. However, most states do not require an official licensing exam.