Data visualizations range from being created with just a paper and pencil sketch to coded with interactive elements. Though data visualization as a discipline does not require any specific tool, there are some software products that are more suitable for specific needs - for example, a quick bar chart in a software you are already familiar with (perhaps Excel or Google Sheets), a dashboard in Tableau, or a network graph in Gephi.
Find more tools for mapping and geo-referencing in the Digital Scholarship and Digital Humanities research guide.