Municipalities within a metropolitan region do not grow in isolation; their development is shaped by pressures diffusing from neighboring jurisdictions through transportation, labor, and housing-market linkages, which conventional city-by-city forecasts cannot exploit. This paper develops a general, network-aware framework for forecasting municipal urban growth in interconnected metropolitan systems. The region is represented as a heterogeneous graph in which each municipality is a node carrying lagged housing, transportation, demographic, and income indicators, and edges encode geographic proximity and socioeconomic similarity. Within this framework we compare a hierarchy of architectures of increasing structure, city-isolated temporal models, spatial graph models, and a spatiotemporal graph model, so that successive comparisons isolate the contributions of temporal structure, spatial structure, and their combination. The prediction target is the year-over-year change in impervious-surface coverage, the planning-relevant increment of newly developed land. We demonstrate the approach on the Dallas–Fort Worth metropolitan area (216 municipalities, 2011–2022). Permutation-based spatial statistics confirm that growth is heterogeneous, temporally autocorrelated, and significantly spatially clustered. Under rolling-origin cross-validation with paired significance tests, graph-based and spatiotemporal models significantly outperform city-isolated baselines, the gain coming from a learned, identity-preserving aggregator rather than the graph alone. Growth exhibits its strongest statistical dependence through short-range geographic proximity rather than socioeconomic similarity. In a validated multi-year forecast, the inter-municipal signal improves prospective accuracy and tempers over-extrapolation of fast-growing fringe municipalities, yielding more accurate, generalizable, and decision-relevant growth forecasts.