Background Emergency department (ED) utilisation and delays are a major public health concern internationally, with increased mortality with ED delays and overcrowding. The study aimed to assess how the population characteristics of ED catchment areas are associated with ED use and delays to admission or discharge, and how catchment presentation rates are associated with ED delays. Methods A cross-sectional study of presentations and delays to all 27 Scottish EDs for December 2023–February 2024. Catchment areas were defined for every ED in Scotland and population demographics for each, as Scottish Index of Multiple Deprivation (SIMD) and 8-fold Urban–Rural Classification (UR8). ED performance metrics for the study period were extracted from routinely reported data. Robust regression assessed the associations between catchment area demographics and ED delays, with negative binomial regression analysis of the association between catchment area demographics and presentation rates for the local population, reported as incidence rate ratio (IRR). Results For each decile lower (more deprived) in median SIMD, monthly attendances increased by 10% (IRR 1.10, 95% CI 1.10 to 1.11). For each step more rural in the median UR8 of a catchment, the percentage of patients experiencing a delay to admission or discharge of over 4 hours reduced by 5.3% (95% CI 4.9% to 5.7%), and each step more deprived in median SIMD decile of a catchment area was associated with 4.8% more delays beyond 4 hours (95% CI 3.0 to 6.8%). There was no association between presentation rates and delay to admission or discharge. Conclusion EDs with more deprived catchment areas have higher presentation rates and greater delays in care. More rural EDs have fewer delays, which may mitigate some of the effects of geographical isolation in the provision of more timely care. In isolation, ED presentation rates are not associated with delays to care, adding to evidence that overall attendances are less important than other factors contributing to ED delays. Policymakers should consider the allocation of resources to best promote health equity.