In many cases, the block numbers correspond to the numbered cross streets; for instance, an address of 1600 may be near 16th Street or 16th Avenue. In a city with both lettered and numbered streets, such as Washington, D.C., the 400 block may be between 4th and 5th streets or between D and E streets, depending on the direction in which the street in question runs. However, addresses in Manhattan have no obvious relationship to cross streets or avenues, although various tables and formulas are often found on maps and travel guides to assist in finding addresses.