For a city that mostly developed when cars were available, I noticed Calgary has relatively narrow lots, even compared to Vancouver/Toronto and definitely narrower compared to the US. I wonder if that is just the timing of development? A guess (with no evidence) I have is that the weather restricts a lot of sprawl. Having giant yards and wide spacing of houses isn't great when there's snow for a good portion of the year. Whereas in Nashville it's more desirable.
Some of it is just good old fashioned government policy.
This area structure plan for "Crowchild 'C'": (what is now Sandstone, Macewan and most of Edgemont, Hawkwood and Arbour Lake) is a 1979 plan that says "An optimum overall density of 22 persons per gross developable acre should be sought." (3.1.4.1.4, pg 40) That translates to 5450 people per square kilometer. That translates to about 7 units per acre (assuming 3.14 people per unit; the citywide average household size in 1981 was 2.81; for new areas like that 3.15 is pretty reasonable.) Later on, it says "The density should be variable between 5 and 15 units per acre depending on local site conditions." for sites with views and near natural corridors. 5 UPA is (at 3.1 people per hh) 3600 people per sq km.
Similarly,
Burlington 1 (Monterey Park), a 1982 plan, similarly envisions 7 units per acre as a baseline. 2007 policies like
East Macleod Trail (Walden / Legacy) specifically require a minimum of 8.5 units per acre overall;
Northeast 'A' (Cityscape/Skyview Ranch/Redstone) requires 8.5 upa as a minimum overall, with 7 as a minimum density most places, and 9.5 near the LRT stations (with nodes of 20+ UPA).
(Link to all the policies)
Historically, the city has required those density levels, and unannexed exurban land was far enough away that we didn't get much of that. It's also just sort of how business has been done historically in Canada. One of my favourite maps to show people to illustrate the difference between Canada and the US is the Sarnia / Port Huron area. (
Link to map). This is north of Detroit, so the Canada-US border is actually the river running north-south through the middle of the map. Same latitude, same climate, same soil, same everything. But you can see the difference:
Sarnia, on the right, has a higher level of density and it is built up continuously, where Port Huron, the US city, sort of fades out but there's this continuous fabric of low-density settlement where there's practically nothing in Canada. The US county on the left, St. Clair county, has 160K people in 1870 sq km - 86 people/sq km, which is actually double the density of the Canadian census division, Lambton County (128K people in 3000 sq km, 43 people per sq km). But Port Huron has under 30K people (and another 10K in Marysville on the south side) while Sarnia has more than twice as many, 72K. But Sarnia's population is in Sarnia; it's not spread out around on acreages, so things like cycling and transit are much more feasible for the majority of the population who don't need to live on a farm..