Thank you so much for writing to us at Ask an Advisor! This is an excellent question; let’s see if we can help you with these efforts.
It’s not always necessary to have someone who has professional organizing experience. However, you definitely want someone (or a group of people) local to the city in which you plan to hold the event who can help with on-site preparations. Ideally, the people who are assisting you on the ground should know who in the city to go to for securing a route, occupancy permits, insuring there are enough police officers staffed that day, acquire any needed event insurance, securing a sound system (if necessary), assisting with advertising the event, and etc.
You said that you have people already located in various cities who could help with the groundwork. Are these people familiar with the general process for organizing a large community event or public demonstration? If not, do they have connections who can provide assistance and guidance? You might want to reach out within your various networks to organize a central steering committee for each site location who can assist with these tasks. It might help to think more broadly—has someone in your contacts organized--if not a march--something similar, such as a charity 5k or community vigil? If so, would they be willing to help your on-the-ground people organize this event, or at least point them in the right direction for assistance? If you have non-profits in the area who have a mission of or vested interest in reducing gun violence, serving Jewish communities, working against anti-Semitism, or similar, you might want to reach out to them to see if they would be willing to co-sponsor the event or provide other support.
If you are planning events in larger cities, it is also possible that the city has a general protocol or set guidelines for securing public areas for community events. You might want to reach out to city hall to see if there are existing protocols that could assist you.
For additional ideas, you may wish to review some of the materials in the Community Tool Box, especially Chapter 33, Conducting a Direct Action Campaign. Section 14, Organizing Public Demonstrations, would be particularly relevant to your work.
We hope that some of these ideas have been helpful to you. Thank you again for writing, and all the best wishes for continued success in your work.