Simplify the following text for a Grade 11 native English-speaking person.
Original: Two other major arteries are also sometimes identified as the northern border of `` lower '' or `` downtown Manhattan '' : Canal Street , roughly half a mile north of Chambers Street , and 23rd Street , roughly half a mile north of 14th Street .
Simplified: Two other major arteries are also sometimes identified as lower Manhattan 's northern border : Canal Street , half a mile north of Chambers Street , and 23rd Street , half a mile north of 14th Street .