Across, Over and Through

On the other side (line) : across and over

Across and over can both be used to mean ‘on the other side of a line, river, bridge, road etc.’

• His village is just across/over the border.
• See if you can jump across/over the stream.

High things: over preferred

We prefer over to say ‘on/to the other side of something high’

• Why are you climbing over the wall? (NOT …across the wall?)

On flat areas; in water: across preferred

We usually prefer across to say ‘on/to the other side of a flat area or surface’, or to talk about movement in water.

• He walked across the field. (NOT … over the field)
• Let’s swim across the river. (NOT … over the river)

But over is sometimes used in British English if there is no idea of arriving at the other side.

• We often walk over the fields in the evening.

Across and through

The difference between across and through is like the difference between on and in. through, unlike across, is used for a movement in a three dimensional space, with things on all sides.

Compare:

• We walked across the desert. (We were on the desert.)
• I walked through the wood. (I was in the wood.)
• We drove across the field.

* We drove through several towns.