The Chicago Business Barometer, also known as the Chicago Purchasing Manager's Index, is similar to the national ISM Manufacturing indicator but at a regional level and is seen by many as an indicator of the larger US economy. It is a composite diffusion indicator, made up of production, new orders, order backlogs, employment, and supplier deliveries compiled through surveys. Values above 50.0 indicate expanding manufacturing activity.

The latest Chicago Purchasing Manager's Index, or the Chicago Business Barometer, jumped to 75.2 in May from 72.1 in April, which is in expansion territory and its highest since 1973. Values above 50.0 indicate expanding manufacturing activity.

Here is an excerpt from the press release:

The Chicago Business BarometerTM, produced with MNI, jumped to 75.2 in May, the highest level since November 1973. Demand provided a boost to business activity, but supply chain constraints remain.

Among the main five indicators, New Orders and Order Backlogs saw the largest gains, while Employment recorded the only decline [Source]