I stumbled upon a few old maps of Austin that illustrate this fact, but they also tell an interesting story about the names of our highways today versus what they were called then.

Here is Austin, 1940. Population 87,930!

Today:  Highway 290 runs through Southwest Austin via Ben White Boulevard, about 4 miles south of downtown, then runs along IH-35 northward through the central corridor, then vectors northeastward about 5 miles north of downtown, heading for Houston.

Then:  Highway 290 ran along what is now Lamar Boulevard (then called Fredericksburg Road), then eastward on Barton Springs, overlapping with Highway 81 on Congress for a few blocks before aligning itself along East 1st Street (aka Cesar Chavez) before taking the current alignment of south Highway 183.  This map says it still leads to Houston, so it must have connected with the current alignment of 290 somewhere further east of Austin.

Other interesting things to note:

• While Hghway 81 still exists in much of the US, running through North Texas and West Central Oklahoma, it no longer exists in the Austin area.  It is roughly the north-south arterial route that Interstate 35 would come to occupy — some Austinites might remember as late as the early 1990’s that the Highway 81 designation could be seen on signage along the IH-35 frontage road.   In 1940, Highway 81 ran along Congress Avenue, Lavaca/Guadalupe (which may have been erroneously listed on this map as Guadalupe Boulevard; it is actually Guadalupe Street, at least today), then followed Georgetown Road past the city limits.  I believe 1940’s Georgetown Road is now today’s North Lamar Boulevard past the Triangle shopping center / 45th Street area.
• State Highway 29 no longer comes anywhere near central Austin, but did back then.  Today it runs from Georgetown (30 miles north) to the city of Burnet (60 miles northwest), and was appropriately named Burnet Road.  Today’s Burnet Road no longer takes you to the city of Burnet, but remains a large arterial road through North Austin.  29 also goes southeastward on this map, emptying out near today’s Bergstrom Airport.  Where it eventually would lead in 1940, I have no idea, as this is no longer the street’s designation (it is now 183).
• Highway 81 was paired with Highway 79, which now ends in Round Rock, 20 miles north.
• State Highway 20 no longer exists, at least anywhere near Austin.  It was also known as Manor Road, which is still a major road today.
• East Avenue is the road that would become Interstate 35.  However, it ended at Manor (at least in naming) and became Cameron Road.  Cameron Road still exists today, but due to the freeway being built out now begins at 51st Street, 2 miles north of where it did in 1940.
• Dam Road is now known as Lake Austin Boulevard.
• There is a road called State Street, roughly where Perry Lane is today, that I believe no longer exists in name (or may take the alignment of other roads).
• Airport Road seems to be the same thing as today’s East 51st Street and also appears to be different from the current Airport Boulevard, which runs along the railroad tracks northwest/southeastward.
• Mansfield Dam (on Lake Travis) was known as Marshall Ford Dam, and the way to get to it was via Hancock Drive (this likely connected as it does today to Ranch Road 2222).

Let’s fast forward to Austin 1953:

The differences in just 10–15 years:

• Lamar Boulevard is named and built out as it is today.  It is still, however, the alignment of Highway 290 on the south side of town.
• The “Interregional Highway” is partially built.  That is today’s Interstate 35; the alternate name Interregional was popular in usage until the 1980’s.  Old school Austinites like myself remember it from maps and street signs, but it is probably an unknown name to many people — Interregional generally only refers to the original build-out of IH-35 from the Colorado River to Cameron Road.
• Highway 290 East now follows its current path, picking back up right past Cameron Road as it does today.
• Highway 183 is built/designated, although it now follows what was Highway 29’s alignment (Guadalupe/Lavaca) in North Austin, and now follows East 7th out of town.  From the Colorado River southward, 183 today is pretty much the same as it was then.
• Highway 71 appears, at least on the east half of the city (overlapped with 183).
• Airport Boulevard is built out.
• Balcones Road seems to follow the current path of Mount Bonnell Road, along the Dry Creek canyon.
• The Yacht Club, which may or may not have existed in 1940, appears on this map where the current Westlake Drive is.
• Barton Springs is listed as Zilker Springs on this map.  That may have been a factual error, or perhaps it was also known as such back in the day.
• Guadalupe Street is actually labeled “THE DRAG”, the enduring popular nickname for the portion between 19th/MLK and 29th.

And finally, here’s a 1956 Humble Oil map of Austin:

• The Interregional Highway now crosses the Colorado River, but does not carry the Interstate 35 designation just yet.
• Highway 183 is now aligned along Airport Boulevard.  Today, 183 is about 2–3 miles east of Airport, but also follows a NW/SE track.
• East 7th Street is also designated as Business 183 and Highway 71.

Subtle things to note on all maps:

• Dean Keeton/26th does not yet exist as built out today, so there was no northern connector road on the UT campus.
• Koenig Lane (2222) does not exist on any map, and therefore was probably just a local street or non-existent until the mid 1950’s.  Given the architecture of the houses/businesses on this street, which are late 1950’s-early 1960’s in origin, it might have just been a residential street that they picked because it connected with 290 at Airport.
• Do Alice Avenue (near 45th and Lamar) or Forest Trail exist anymore?
• Mopac is not even shown as a railroad track much less a proposed highway.  It was not built until the late 1960’s-late 1970’s.
• West Lake Hills or Rollingwood do not exist on the map (and I am not sure if there were any subdivisions in this part of town yet).
• Austin was balanced in terms of east vs. west.  Today, the west and north sides sprawl many many more miles than the east or south sides do.  There are suburbs in continuous development for 25 miles north and west, but Austin pretty much ends about 6–7 miles east and about 10 miles south.

In 1940, Austin had 87,930 people; in 1950, 132,459 people, and in 1960, 186,545. As a frame of reference, Austin’s city population is 757,688 today (as of the 2007 census estimate), and the metropolitan area is 1,652,602, the 2nd fastest growing in the nation.