The Census 2000 Redistricting Summary File contains summary statistics on counts for the total population, for the population 18 years and over, and population counts by race and by Hispanic or Latino origin. Data are available for many geographic areas, including states, counties, places, census tracts, and blocks. 

For State Of Maryland :

Data are splits into two files: total population and population 18 years and over. 
Geographic areas are available for states, counties, places, census tracts, block groups and blocks as following :

(Data files for state, counties, places, census tracts and block groups are in Excel (XLS) format. Data files for blocks are in Database (.DBF) format and zipped. The unzipped files are 109MB in size. The most efficient way to use the block data is saving it onto your hard drive before viewing it.)