The counties that are contiguous with Ottawa County are:
 Muskegon, Kent and Allegan.  
(Oceana County was formed in 1831 from Ottawa County)

Ottawa County was "created" in 1831, organized in 1837,  parent county/ies being 
 Michilimackinac (unorganized land) & Kent
<http://resources.rootsweb.com/USA/MI/Ottawa/>

Muskegon County came into being in 1859, when Ottawa County was divided. This page is a member of the MIGenWeb Project County Web Sites at RootsWeb - Muskegon MI

Kent County was established about 1836. This page is a member of the MIGenWeb Project
County Web Sites at RootsWeb - Kent MI

Allegan County was created abt. 1831. Part of the City of Holland is in Allegan Co. today. 
There are 3 sources for genealogy & history information:
Here is the MiGenWeb Page for Allegan County
 County Web Sites at RootsWeb - Allegan MI