Nashua () is a city in southern New Hampshire, United States. As of the 2020 census, it had a population of 91,322, the second-largest in northern New England after nearby Manchester. Along with Manchester, it is a seat of New Hampshire's most populous county, Hillsborough. Built around the now-departed textile industry, in recent decades Nashua's economy has shifted to the financial services, high tech, and defense industries as part of the economic recovery that started in the 1980s in the Greater Boston region. Major private employers in the city include Nashua Corporation, BAE Systems, and Teradyne. The city also hosts two major regional medical centers, Southern New Hampshire Medical Center and St. Joseph Hospital. The South Nashua commercial district is a major regional shopping destination, lying directly on the Massachusetts border and taking advantage of New Hampshire's lack of sales tax. It is anchored by the Pheasant Lane Mall and numerous smaller shopping centers. It is one of several U.S. cities nicknamed Gate City, which references a reputation for being a travel gateway - in this case between the Boston region and New Hampshire. A number of civic groups and institutions have adopted the title.