The state Board of Elections says:
To register and vote during early voting, go to an early voting center [there’s one at Towson University at 7720 York Road, with free parking in the lot accessed via Cross Campus Drive] in the county where you live and bring a document that proves where you live. This document can be your MVA-issued license, ID card, or change of address card, or your paycheck, bank statement, utility bill, or other government document with your name and new address. You will be able to register to vote and vote.
When can I vote early?
2016 Presidential Elections
Where can I vote early?
You can vote in an early voting center in the county where you live. See a list of the 2016 Primary early voting sites (PDF).