In the history of our city, we've never seen this much rain. Up to 56" fell during Hurricane Harvey, pushing our yearly total to 73.51" as of 11:30am today. That's a new record for annual rainfall! As I write this, it's pouring so I expect that number to eclipse 74"-75" before the day's out. We still have three months to go in this year, so we'll likely see 80"+ before 2018.
The old record was 72.86" achieved 117 years ago, in 1900. The normal total for any given year at Houston's official recording station (Bush Intercontinental Airport) is 49.16". In Houston downtown, that the yearly rainfall averages to 46.15". So, we are nearly 2 feet above normal and we still have 90 days to go before the turn of the New Year.
In the context of the geologic history of southeast Texas and the coordinates where Houston resides, this area has no doubt seen even more rain in years before the city was physically here, but in the context of our lifetimes and the history of the city of Houston, this is a superlative.
Also note: Weather records have only been reliably kept since the late 1800s and especially after 1969 (when the official reporting station moved from downtown Houston to the Humble area at Bush IAH), so we've only been watching the region a tiny window in the big picture of our region's history. That said, we may not see this kind of rain for quite a while, if not ever again in our life!