In San Diego the coast is ripe with shipyards, churning out ship after ship. I won't pretend to be a boat expert but they definitely look like military warships. San Diego is known as a navy/marine city, and there are forts and bases all around.
In poor parts of every city I've been to, however, the police are obnoxiously present in every corner, and though they leave the heavy gear back at the precinct, everyone knows what the PD packs.
A military parade has two functions: to embolden the "patriots" of a country, and to scare the downtrodden of a country. These functions are largely served by civilian gun shows, air shows, and fireworks shows throughout much of the country, and what zealous citizens don't do the police are more than happy to make up for. Then the actual military (which is mostly abroad, generating profit) is present in the actual States mostly as a benevolent job-creator, with industrial projects and recruitment/administrative centers where there are lots of people.
In America we don't need the military to show off the strength of the government in our city streets because we'll do it ourselves.