How do you know a song is a march without reading the title?

Well, recognizing a march is not that hard when you know the ways they are distinct, making the march one of the easiest forms to recognize. 

First is the time signature. Almost all marches are in cut time, 4/4, 2/2, 1/2, or 2/4. These are all identical, even though they may sound different. Most marches are at a brisk tempo, and have a strong rhythmic pulse. Tubas or sousaphones are use in marches to provide an ohm-pah sound, so if the tuba or sousaphone part has quarter notes going up and down, you are likely looking at a march.

The percussion in a march is usually a snare drum and glockenspiel. As time went on, marching tympani, crash cymbals, and bass drum. Snare will play something rudimentary, with rolls and taps and a little syncopation. Bass and tympani will have quarter notes and eighth notes. Crash cymbals may have unison with the bass drum, or a unique rhythm alongside it.

The basic form of the march is an exposition, a trio, and a repeat of the exposition. The exposition will be in 16 or 32 measure strains, and the trio will modulate to the sub-dominate key. The repeat of the exposition concludes the piece, or the piece will loop ad-nauseum.

The instrumentation often includes piccolos or flutes to carry the melody, while lower instruments play a harmony. This is because early marches were used in war, and high instruments cut through the loud sounds. Drums imitate marching feet, and keep troops steady.