Name one street that is parallel to Harrison Street.

It runs in a North-South direction.

One such street is Simmonds Street.
Another example is Fraser Street.
Answer: $\boxed{\text{Simmonds Street}}$

It runs in an East-West direction.

One such street is Fraser Street.
Another example is Sauer Street.
Answer: $\boxed{\text{Fraser Street}}$

• East along the unnamed street to Sauer Street: Approximately 0.5 blocks.
• South on Sauer Street from the unnamed street to President Street: 1 block (from the level of Pritchard Street to President Street).
• East on President Street from Sauer Street to Rissik Street: 4 blocks (Sauer $\to$ Fraser $\to$ Simmonds $\to$ Harrison $\to$ Rissik).
• South on Rissik Street from President Street to the Post Office: Approximately 0.5 blocks (the Post Office is between President and Market Streets). Total blocks walked = $0.5 + 1 + 4 + 0.5 = 6$ blocks.

Visually, the distance between two adjacent parallel streets (e.g., President and Market, or Harrison and Simmonds) is approximately $1.5 \text{ cm}$ on the map.

The scale is $1 \text{ cm} = \frac{1}{2} \text{ km}$.

Thabo walks approximately $\boxed{4.5 \text{ km}}$.