Since the passage of the Public Employees Labor Relations Act (RSA 273-A), New Hampshire has seen explosive growth in the number of county, municipal and school district employees who are unionized. Prior to the 1970s, unionization had occurred in only a few New Hampshire communities. Since the adoption of RSA 273-A, it has become common for public employees to unionize as soon as they can form a bargaining unit that meets the minimum statutory requirements of ten regular full or part-time employees, or both, who share a "community of interest."