Thanks for reaching out @gbbuggs. At the moment there are two ways I think you could approach this.
1. You can put the location of each volunteer opportunity within the main content of each. That would make the location searchable using the default WordPress search.
2. You could create individual pages for each location and link from those pages to each opportunity at that location. For example, you could have pages called “St. Louis Volunteer Opportunities”, “Chicago Volunteer Opportunities”, “Austin Volunteer Opportunities”, etc. Then you could create a landing page called something like “Volunteer Opportunities” with links to each location’s page. This is a more manual approach than using the shortcodes or option 1 above, but it would allow visitors to see the volunteer opportunities that are specific to a given location.
Let me know if you have any questions.
Jonathan