Geographical diversity has absolutely nothing to do with a Grand Slam. While you can debate, endlessly, the merit of certain tournaments the simple fact remains that the term Grand Slam can only ever refer to the Australian, French, Wimbledon and US Opens. It doesn't refer to professional events and it doesn't refer to any other amatuer events, only those four mentioned. Just consider that it is really only from the Crawford era onwards that the leading players did compete in all of the major amatuer events. So, that the Grand Slam didn't exist before that time is particularly apt.
Also, if you are going to factor in how players fared outside their own nation, you would seriously devalue Gonzalez's achievements although, to a certain degree, that should be done.
As to the use of cement courts. They were in place as a surface option from the early days of tennis in the United States, Australia and the United Kingdom. I can't say when the first one came into being, however, cement was used in California (Santa Monica) from 1879. The proliferation of cement courts on the West Coast of the United States (probably on public courts) was the reason so many players used a Western grip on the forehand (to counter the high bounce). Don Budge, who grew up on those courts had to alter his grip to something closer resembling Eastern when he began to compete in the grasscourt circuit.
Also, if you are going to factor in how players fared outside their own nation, you would seriously devalue Gonzalez's achievements although, to a certain degree, that should be done.
As to the use of cement courts. They were in place as a surface option from the early days of tennis in the United States, Australia and the United Kingdom. I can't say when the first one came into being, however, cement was used in California (Santa Monica) from 1879. The proliferation of cement courts on the West Coast of the United States (probably on public courts) was the reason so many players used a Western grip on the forehand (to counter the high bounce). Don Budge, who grew up on those courts had to alter his grip to something closer resembling Eastern when he began to compete in the grasscourt circuit.