crowding levels. We then compared the adoption of crowding measure across quartiles and compared differences using linear regression using 2010 data. All analyses were adjusted for complex survey design and weighting to provide national estimates (SAS 9.3); P<.05 was significant.Results: There was a significant increase for seven crowding interventions from 2007 to 2010 including use of bedside registration (66.3% in 2007 to 79.2% in 2010, P¼.0019), electronic dashboards (35.2% to 51.9%, P¼.0024), radio frequency identification tracking (9.8% to 20.7%, P¼.0216), full capacity protocol (21.0% to 45.6%, P<.001), boarding patients on inpatient hallways (14.8% to 23.8%, P¼.027), immediate bed census availability (66.1% to 83.4%, P<.0001), and use of pooled nurses (33.2% to 60.0%, P<.0001). The total number of interventions rose from 5.2 to 6.6 from 2007 to 2010 (P<.0001). Several crowding interventions demonstrated no change over the study period, such as computer-assisted triage, presence of fast-track, increased number of standard ED treatment spaces, physical expansion of the ED, zone nursing, use of a bed czar, avoiding admissions when on ambulance diversion, presence of a separate OR for ED cases, or surgical schedule smoothing. The use of an ED observation unit decreased (35.7% to 21.1%, P<.0001). In 2010, six specific interventions showed greater use in more crowded EDs (Table). By comparison, use of bed census availability and avoiding admissions of elective cases during ambulance diversion were inversely related to ED crowding. Adoption of the remainder of the interventions was not associated with ED crowding levels.Conclusion: There has been a growth in the number of interventions to reduce ED crowding across U.S. hospitals from 2007-2010, several which reflect technological advances. However, interventions that required a change in hospital-level protocols demonstrate relatively low adoption rates and have not grown in use, potentially because of difficulties in accomplishing hospital-wide interventions or priorities. In general, EDs that were more crowded have adopted more strategies, demonstrating that interventions are being used in hospitals with the greatest need. Table. Adoption of interventions in crowded EDs Overall Quartile #1 Quartile #2 Quartile #3 Quartile #4 P value Computer-assisted triage 49.3% 36.3% 52.7% 66.3% 75.3% <.0001 Electronic dashboard 51.9% 36.5% 58.6% 69.9% 81.1% <.0001 Fast-track 39.7% 23.8% 43.1% 63.3% 69.6% <.0001 Zone nursing 44.6% 28.5% 59.0% 58.2% 66.6% .0006 Bed czar 59.2% 46.7% 64.0% 78.4% 77.7% .0031 Bed census availability 83.4% 87.1% 90.7% 63.6% 79.4% .0281 Avoid admission of elective cases when on ambulance diversion 79.2% 93.2% 69.9% 60.0% 63.4% <.0001 Total crowding interventions 6.55 5.65 6.94 7.60 8.26 <.0001