The unequal income distribution within and across cities have been attracting substantive attention. To obtain a dynamic view of urban income inequality, indices and their subgroup decompositions are usually estimated for each cross section and a tentative conclusion could be reached in terms of whether the overall income inequality as well as the intra- and inter-regime inequality decreases over time. It should be noted that it is the consequence of the income mobility of spatial aggregates (e.g. census tracts) instead of the nature of the mobility that is revealed. In this paper, we employ an income mobility index based on the absolute income difference to reveal the spatial dimension of the multifaceted urban income mobility in the United States. We first apply spatial regionalization to socioeconomic variables which are aggregates for census tracts to delineate homogeneous neighborhoods within each of 366 metropolitan statistical areas in the United States. Then the income mobility index is decomposed into intra- and inter-neighborhood components to reveal the spatially heterogeneous mobility contributions from neighborhoods. A further decomposition for intra- and inter-neighborhood income mobility is made which results in three contributing components - exchange, growth and dispersion mobility. The research sheds light on the urban income mobility from a comprehensive multidimensional and spatial perspective and serves as a building block for further research investigating the determinants of the contributing mobility components.