When you have gone from one side of a street to the other side, you have gone across the street—–not acrossed the street, acrosst the street, or acrost the street. I’m not sure how people who use this non-word are spelling it, and I guess it doesn’t matter since it isn’t a word.

I crossed at the light and ran across the street to take the subway across town, where I ran across an old boyfriend to whom I warned, “Don’t cross me.”

Sherry

Paul’s book–Literally, the Best Language Book Ever;

Sherry’s Grammar List