McHenry is unique in that its development and geography make classifying it in one particular region or another exceptionally difficult. The southeastern portions, which are heavily developed, might be said to properly belong with the greater Chicagoland region, while the western and northern areas gravitate toward other region centers. In general, McHenry County can be divided to belong to the following regions:
- Chicagoland's Northwestern Suburbs: Algonquin, Crystal Lake, Cary, Huntley and Lake in the Hills share many characteristics with Chicagoland's other northwestern suburbs and may be properly assigned there.
- Chicagoland's Chain O'Lakes: The extreme northeastern portion of the County, including Spring Grove and Richmond, share many economic characteristics with the rest of the Chain O'Lakes communities.
- Northern Illinois's Kishwaukee Valley: Woodstock, Marengo, Harvard and Hebron tend to be culturally and economically related to the Rockford area and may be assigned to the Kishwaukee River Valley. The northern branch of the river rises near Woodstock.
- 1 Algonquin, a large, suburban community located mostly in McHenry County with a small portion in Kane County. Located directly on the Fox River and home to the large outdoor shopping area called Algonquin Commons.
- 2 Cary, a small, suburban community in the southeastern portion of the County.
- 3 Crystal Lake, a suburban community located in the southeastern portion of the County. It is known for its downtown.
- 4 Harvard, a rural community in the northwestern portion of the County. Known for its annual Milk Days celebration.
- 5 Hebron, a rural community in the northern part of the County. Known regionally for its painted water tower which commemorates a high basketball State Championship.
- 6 Huntley, a relatively new suburban community located on I-90 and partially located in Kane County.
- 7 Lake in the Hills, a suburban community located near I-90.
- 8 Richmond, a rural community in the northeastern portion of the County. It sits along US 12 and is immediately adjacent to Genoa City.
- 9 Spring Grove, a suburban community located in the northeastern portion of the County along US 12.
- 10 Woodstock, the county seat and known for its Opera House and historic downtown.
McHenry County is a formally mostly rural county which may be considered part of both the Chicagoland and greater Northern Illinois region. With the expansion of I-90 and daily commuter service to Chicago, many parts of the county (specifically the southeastern and southern portions) became increasingly developed and are now considered suburbs of Chicago. However, many portions of the county (particularly the western and northern regions) are still largely rural. The modern day county is a mixture of old and new but remains largely politically conservative. It continues to be one of the fastest growing areas of the region.
McHenry County is most accessible using I-90 from either Chicago or Rockford. However, many other arterial routes cross the area including US 14 (passes through most major communities in the County), US 12 (passes immediately to the east of the County and then through Richmond) and US 20 (passes to the south and then through Marengo). A number of State routes also crisscross the County.
Metra, the greater Chicagoland passenger rail system, offers daily service to and from Chicago's Ogilvie Station on the Union Pacific Northwest Line via a number of communities in the County including Harvard, Woodstock, McHenry, Crystal Lake, Pingree Road (second Crystal Lake stop) and Cary. Service may terminate in Crystal Lake, McHenry or Harvard depending on the train.
By and large, McHenry County is safe.