USD to AUD Historical Exchange Rate
Back in 1966 when the Australian dollar was first introduced, it was actually fixed against the British pound at an equivalent value of one gram of gold. The peg was adjusted to US dollars on 9th September 1973 and set at A$1 to US$1.4875.
The Australian dollar was floated on 12th December 1983, which meant that its value could now fluctuate based on international money markets and supply and demand.
The following two decades saw the Australian dollar reach a high of 1 AUD to 0.881 USD in December of 1988, and a low of $0.477 in April 2001. By June 2008, it had risen significantly to $0.96, and continued to rise to $0.98 by the end of that same year.
On 15th October 2010, the US dollar rose higher than the Australian dollar for the first time since the AUD becoming a floating currency; trading a little above AUD$1 for a few seconds. That November, the US dollar actually traded above the Aussie dollar for several days and stayed around there well into 2011. On the 27th July the US dollar hit a record high against the Aussie, trading at $1.108.
The US dollar has been trading below the Aussie dollar since October of 2013, falling all the way to 0.69 in September of 2015.