 However, in the 1970s, the increasing use of automation caused the number of stations to contract.In 1976, for example, NMN (then at Communication Station (COMMSTA) Portsmouth) assumed the duties of NMH in Washington, and took over remote operations from Miami in 1993, Boston (NMF) in 1996, and New Orleans in 1998.With the introduction of the computer-assisted Rescue 21 system, the ability of the Coast Guard to provide coverage on the marine VHF band in marginal areas has increased.