The cornerstone of the land-use program, the urban growth boundary (UGB), represents a planning tool qualitatively different from traditional land-use regulations. The qualitative difference lies in the addition of a new dimension-the dimension of timing. Whereas traditional land-use regulations specify what, where, and how one can improve land, the UGB specifies when one can improve land. In Oregon, current land usage both inside and outside UGBs is regulated by traditional land-use controls-e.g., zoning, tax incentives, fee simple, and building codes-future land usage is regulated by UGBs. Specifically, only land inside a UGB can be converted to urban use before a specified date; land outside a UGB is preserved for nonurban use until after the same specified date.