Background: The endemic region of blastomycosis historically has included the state of Indiana. However, few published reports of blastomycosis exist to substantiate this distinction. A surge of patients with blastomycosis in central Indiana (Indianapolis and surrounding counties) beginning in 2005 prompted us to review our local experience. We propose that this surge was related to major highway construction around Indianapolis. Methods: We reviewed all microbiologically confirmed cases from four hospitals serving central Indiana. Chart review was completed for adult patients, and data were collected on clinical presentations, methods of diagnosis, comorbidities, radiologic findings, treatment, and outcomes. We plotted patient residence addresses with sites of highway construction. Results: Fifty-nine patients were identified from laboratory results and physician referral. Interestingly, a surge of blastomycosis incidence occurred in 34 patients between 2005 and 2008 during which time major highway projects were under way around the Indianapolis metropolitan area. The majority of these patients presented acutely and with pulmonary involvement. Fungal culture and antigen testing were the most sensitive means to diagnosis. Antifungal therapy was highly effective. Conclusions: This urban outbreak of blastomycosis in Indianapolis should prompt clinicians to consider blastomycosis in this highly endemic area of histoplasmosis.