Digitization started quite early (1960s) but it did not finish until decades later. The first transatlantic fibre optic cable was only laid in 1988. Before that communication between North America and Europe was analog. The Internet and other networks of that time linked over the Atlantic with modems over satellite or voice channels on the analog coaxial submarine cables.

TAT-7 - 4000 analog 3 kHz channels over coaxial, laid 1983

TAT-8 - 280 Mbit/s over fibre optic, laid 1988