Several Maryland counties are conducting a homeless persons count this time of year. The census is required by the Federal Department of Housing and Urban Development (HUD) and helps them decide what funding should be allocated toward homelessness. The last time the census was taken in Baltimore, 4,000 people were counted as homeless.
This link will take you to HUD's Annual Homelessness Assessment Report from last year. Page 5 includes a map of the US with the share of the country's homeless population broken down by state.