Wisconsin Avenue - Building Numbering

Building Numbering

One aspect of Rockville Pike that confuses many motorists is the system of assigning building numbers. In unincorporated areas of the county, building numbers are assigned according to the addressing system in use in Montgomery County, a Cartesian coordinate plane with its origin at the United States Capitol. Within the city limits of Rockville, however, the origin of the numbering system is at the center of Rockville. Thus, someone driving north on the Pike sees building numbers above 12000 and rising, which suddenly give way to building numbers below 2000 and falling.

In Gaithersburg, the numbering direction changes twice. Addresses on South Frederick Avenue increase from zero as one travels south from Diamond Avenue, and only reach the hundreds by the southern city boundary. On North Frederick Avenue, the numbers similarly increase from zero as one travel to the north. As one leaves Gaithersburg to the north, the building numbers change back to the county's Capitol-based system.