1. Bureau's Longitudinal Business Database (LBD), a near-universe of establishments operating with positive employment in the United States, from 1975-2015 (for this project I have access to data starting from 1985). In the LBD, an establishment is defined as a specific physical location where business occurs. The LBD contains information on payroll, employment, industry, and location. In addition to establishment-level identifiers, the LBD contains enterprise-level identifiers;The establishment-level data is drawn from the U.S. Census
2. While the variable name is firmid, this is distinct to the firm-level identifier that is available in the LEHD, which is the EIN. Therefore, throughout the paper, I refer to the firmid available in the LBD as the enterprise ID. lbdnum: The establishment-level identifier that indicates a single physical location. The identifier is time-invariant and does not change due to changes in ownership of the establishment. Employment: Establishment-level employment as of March 12 th;B.1.2 LBD Variable Definitions firmid: The enterprise-level identifier that identifies the ultimate ownership of the establishment
3. Census switched from using Standard Industrial Classification (SIC) to NAICS. While most of the analysis in the paper does not require industrial classification pre-1997 (I study mergers 1999-2009), the analysis that does require pre-1997 industrial classification uses time-consistent NAICS;Industry: Unless otherwise stated, industry is defined by 4-digit North American Industry Classification Systems (NAICS) codes,1997