Along and Across
Along follows the length of something linear; across crosses from one side to the other of a flat surface. Both describe movement on surfaces, but in different directions.
Along and Across: Following vs Crossing
Both prepositions describe surface movement, but the direction differs relative to the surface. Research on B1–B2 learner corpora shows that along/across confusion is particularly common with nouns like 'bridge', 'corridor', 'river', and 'road', where learners must identify whether movement follows the surface lengthwise or cuts across it. A secondary error is substituting 'on' or 'through' for 'along'.
Along — Following the Course of Something Linear
Use along when movement follows the direction or length of a linear feature — a river, a road, a coast, a path, a corridor:
They drove along the coast, stopping at small towns on the way.
We strolled along the beach, looking for shells.
Across — From One Side to the Other of a Surface
Use across when movement goes from one edge to the opposite edge of a flat surface or open area:
The children swam across the pool to see who was fastest.
She ran across the road and along the river bank.
Telling Them Apart
Ask: am I moving parallel to the feature (along) or perpendicular to it (across)? Walking along the river = same direction as the river. Swimming across the pool = from one end wall to the other.
Common Mistakes
✗ We walked through the bridge. → ✓ We walked across the bridge.
✗ They cycled on the river path. → ✓ They cycled along the river path.
✗ We walked on the river bank. → ✓ We walked along the river bank.