Government Purchases Line

A representative government purchases line is presented in the exhibit to the right. This red line, labeled G in the exhibit, is positively sloped, indicating that greater levels of income generate greater government purchases by the government sector. This positive relation indicates that the government sector, especially state and local governments, is inclined to use increasing tax revenue generated by an expanding economy for government purchases.

The government purchases line graphically illustrates the government purchases-income relation for the government sector, which is then added to the consumption line to derive the aggregate expenditures line used in Keynesian economics to identify equilibrium income and production.

The intercept of the government purchases line indicates the intersection point between the government purchases line and the vertical government purchases axis. The government purchases line intersects the vertical axis at a value of $2 trillion. Theoretically, this is a minimum "baseline" level of government purchases, the amount of government purchases undertaken if aggregate income falls to zero. This intersection indicates autonomous government purchases--government purchases unrelated to income. Click the [Intercept] button to illustrate.

Autonomous government purchases are government purchases by the government sector that are unrelated to and unaffected by the level of income or production. This is best indicated by a zero level of income. While individual government entities might come face-to-face with autonomous government purchases, as their own slice of aggregate tax revenue drops to zero, for the aggregate economy autonomous government purchases are mostly an unlikely theoretical extrapolation.