This is how big the Internet was back in 1975... aka the Arpanet
The ARPANET geographical map now shows 61 nodes. Licklider arranges its administration to be turned over to the Defense Communications Agency (DCA). BBN remains the contractor responsible for network operations. BBN agrees to release the source code for IMPs and TIPs.
The Network Working Group maintains its open system of discussion via RFCs and e-mail lists. Discomfort grows with the bureaucratic style of DCA.
The Department of Energy creates its own net to support its own research. This net operates over dedicated lines connecting each site to the computer centers at the National Laboratories.
NASA begins planning its own space physics network, SPAN. These networks have connections to the ARPANET so the newly developed TCP protocol begins to get a workout. Internally, however, the new networks use such a variety of protocols that true interoperability is still an issue.