diff --git a/collects/web-server/default-web-root/servlets/examples/quiz.ss b/collects/web-server/default-web-root/servlets/examples/quiz.ss
index f8bd28b89a..185dea192c 100644
--- a/collects/web-server/default-web-root/servlets/examples/quiz.ss
+++ b/collects/web-server/default-web-root/servlets/examples/quiz.ss
@@ -118,7 +118,7 @@
          csw)))
     (list 0 0 0) questions answers))
 
- ;; end-quiz: (listof question) (listof (union number false)) -> request
+ ;; end-quiz: (listof question) (listof (or/c number false)) -> request
  ;; request bindings are not currently used.
  (define (end-quiz questions answers)
    (send/forward
diff --git a/collects/web-server/dispatch-passwords.ss b/collects/web-server/dispatch-passwords.ss
index 223cabd8a5..539c8fcbe4 100644
--- a/collects/web-server/dispatch-passwords.ss
+++ b/collects/web-server/dispatch-passwords.ss
@@ -45,8 +45,8 @@
   ;; pass-entry = (make-pass-entry str regexp (list sym str))
   (define-struct pass-entry (domain pattern users))
   
-  ;; access-denied? : Method string x-table denied? -> (+ false str)
-  ;; denied?: str sym str -> (U str #f)
+  ;; access-denied? : Method string x-table denied? -> (or/c false str)
+  ;; denied?: str sym str -> (or/c str #f)
   ;; the return string is the prompt for authentication
   (define (access-denied? method uri-str headers denied?)    
     (let ([user-pass (extract-user-pass headers)])
@@ -56,7 +56,7 @@
   
   (define-struct (exn:password-file exn) ())
   
-  ;; : host -> (str sym str -> (U str #f))
+  ;; : host -> (str sym str -> (or/c str #f))
   ;; to produce a function that checks if a given url path is accessible by a given user with a given
   ;; password.  If not, the produced function returns a string, prompting for the password.
   ;; If the password file does not exist, all accesses are allowed.  If the file is malformed, an
@@ -74,7 +74,7 @@
                    (map (lambda (x) (make-pass-entry (car x) (regexp (cadr x)) (cddr x)))
                         raw))])
             
-            ;; string symbol bytes -> (union #f string)
+            ;; string symbol bytes -> (or/c #f string)
             (lambda (request-path user-name password)
               (ormap (lambda (x)
                        (and (regexp-match (pass-entry-pattern x) request-path)
diff --git a/collects/web-server/dispatch-servlets.ss b/collects/web-server/dispatch-servlets.ss
index baefe6e213..577309756b 100644
--- a/collects/web-server/dispatch-servlets.ss
+++ b/collects/web-server/dispatch-servlets.ss
@@ -275,7 +275,7 @@
                  (string->immutable-string (format "Couldn't find ~a" servlet-filename))
                  (current-continuation-marks) ))]))
     
-    ;; load-servlet/path path -> (union #f cache-entry)
+    ;; load-servlet/path path -> (or/c #f cache-entry)
     ;; given a string path to a filename attempt to load a servlet
     ;; A servlet-file will contain either
     ;;;; A signed-unit-servlet
diff --git a/collects/web-server/request-parsing.ss b/collects/web-server/request-parsing.ss
index 6783243511..9c18a7347b 100644
--- a/collects/web-server/request-parsing.ss
+++ b/collects/web-server/request-parsing.ss
@@ -16,7 +16,7 @@
   (provide/contract
    [read-request ((connection? number? ((input-port?) . ->* . (string? string?))) . ->* . (request? boolean?))]
    [read-bindings (connection? symbol? url? (listof header?)
-                               . -> . (union (listof binding?) string?))])
+                               . -> . (or/c (listof binding?) string?))])
   
   
   ;; **************************************************
@@ -70,13 +70,13 @@
   ;; **************************************************
   ;; read-request-line
 
-  ; Method = (U 'get 'post 'head 'put 'delete 'trace)
+  ; Method = (or/c 'get 'post 'head 'put 'delete 'trace)
   (define METHOD:REGEXP
     (byte-regexp #"^(GET|HEAD|POST|PUT|DELETE|TRACE) (.+) HTTP/([0-9]+)\\.([0-9]+)$"))
 
   (define (match-method x)
     (regexp-match METHOD:REGEXP x))
-  ;:(define match-method (type: (str -> (union false (list str str str str str)))))
+  ;:(define match-method (type: (str -> (or/c false (list str str str str str)))))
 
 
   ; read-request-line : iport -> symbol url number number
@@ -106,7 +106,7 @@
 
   (define (match-colon s)
     (regexp-match COLON:REGEXP s))
-  ;:(define match-colon (type: (str -> (union false (list str str str)))))
+  ;:(define match-colon (type: (str -> (or/c false (list str str str)))))
 
 
   ; read-headers : iport -> (listof (cons symbol bytes))
@@ -143,7 +143,7 @@
 
   (define INPUT-BUFFER-SIZE 4096)
 
-  ;; read-bindings: connection symboll url (listof header?) -> (union (listof binding?) string?)
+  ;; read-bindings: connection symboll url (listof header?) -> (or/c (listof binding?) string?)
   (define (read-bindings conn meth uri headers)
     (case meth
       [(get) (url-query uri)]
@@ -231,7 +231,4 @@
                                null
                                (cdr body)))])))
 
-  (define CR-NL (format "~a~a" #\return #\newline))
-
-
-  )
+  (define CR-NL (format "~a~a" #\return #\newline)))
diff --git a/collects/web-server/request-structs.ss b/collects/web-server/request-structs.ss
index 2cbaeb1ae3..a017f0e4fb 100644
--- a/collects/web-server/request-structs.ss
+++ b/collects/web-server/request-structs.ss
@@ -15,12 +15,12 @@
   ;; is this a binding
   (define binding?
     (cons/c symbol? 
-            (union string?
+            (or/c string?
                    bytes?)))
 
   (provide header? binding?)
   (provide/contract
    [struct request ([method symbol?] [uri url?] [headers (listof header?)]
-                    [bindings/raw (union (listof binding?) string?)]
+                    [bindings/raw (or/c (listof binding?) string?)]
                     [host-ip string?] [host-port number?]
                     [client-ip string?])]))
\ No newline at end of file
diff --git a/collects/web-server/response-structs.ss b/collects/web-server/response-structs.ss
index ff57ea9149..337c15e7ab 100644
--- a/collects/web-server/response-structs.ss
+++ b/collects/web-server/response-structs.ss
@@ -54,7 +54,7 @@
             [seconds number?]
             [mime bytes?]
             [extras (listof (cons/c symbol? string?))]
-            [body (listof (union string?
+            [body (listof (or/c string?
                                  bytes?))])]
    [struct (response/incremental response/basic)
            ([code number?]
@@ -62,6 +62,6 @@
             [seconds number?]
             [mime bytes?]
             [extras (listof (cons/c symbol? string?))]
-            [generator ((() (listof (union bytes? string?)) . ->* . any) . ->
+            [generator ((() (listof (or/c bytes? string?)) . ->* . any) . ->
                                                                          . any)])]
    [response? (any/c . -> . boolean?)]))
\ No newline at end of file
diff --git a/collects/web-server/servlet-helpers.ss b/collects/web-server/servlet-helpers.ss
index 90eb09c2f0..6c67cb7132 100644
--- a/collects/web-server/servlet-helpers.ss
+++ b/collects/web-server/servlet-helpers.ss
@@ -222,9 +222,9 @@
   
   (define AUTHENTICATION-REGEXP (regexp "([^:]*):(.*)"))
   (define (match-authentication x) (regexp-match AUTHENTICATION-REGEXP x))
-  ;:(define match-authentication (type: (str -> (union false (list str str str)))))
+  ;:(define match-authentication (type: (str -> (or/c false (list str str str)))))
   
-  ; extract-user-pass : (listof (cons sym bytes)) -> (U #f (cons str str))
+  ; extract-user-pass : (listof (cons sym bytes)) -> (or/c #f (cons str str))
   ;; Notes (GregP)
   ;; 1. This is Basic Authentication (RFC 1945 SECTION 11.1)
   ;;    e.g. an authorization header will look like this:
@@ -244,7 +244,7 @@
                      (cons (cadr user-pass) (caddr user-pass)))]
                [else #f])))))
   
-  ;; basic?: bytes -> (union (listof bytes) #f)
+  ;; basic?: bytes -> (or/c (listof bytes) #f)
   ;; does the second part of the authorization header start with #"Basic "
   (define basic?
     (let ([basic-regexp (byte-regexp #"^Basic .*")])
diff --git a/collects/web-server/servlet-tables.ss b/collects/web-server/servlet-tables.ss
index 619ed336b8..58bb1f4c3d 100644
--- a/collects/web-server/servlet-tables.ss
+++ b/collects/web-server/servlet-tables.ss
@@ -38,7 +38,7 @@
   (provide
    match-url-params)
   (provide/contract
-   [continuation-url? (url? . -> . (union boolean? (list/c symbol? number? number?)))]
+   [continuation-url? (url? . -> . (or/c boolean? (list/c symbol? number? number?)))]
    [embed-ids (symbol? number? number? url? . -> . string?)]
    [store-continuation! (procedure? procedure? url? servlet-instance? . -> . string?)]
    [create-new-instance! (hash-table? custodian? execution-context? semaphore? timer?
@@ -130,7 +130,7 @@
      in-url
      (format "~a*~a*~a" inst-id k-id salt)))
 
-  ;; continuation-url?: url -> (union (list number number number) #f)
+  ;; continuation-url?: url -> (or/c (list number number number) #f)
   ;; determine if this url encodes a continuation and extract the instance id and
   ;; continuation id.
   (define (continuation-url? a-url)
diff --git a/collects/web-server/tools/send-assertions.ss b/collects/web-server/tools/send-assertions.ss
index 4890320440..bfb06e541f 100644
--- a/collects/web-server/tools/send-assertions.ss
+++ b/collects/web-server/tools/send-assertions.ss
@@ -20,7 +20,7 @@
 
   #|
   (define in?
-    (union
+    (or/c
       (list-immutable/c (xexpr/callback? . -> . string?)
                         (listof (cons/c symbol? string?)))
       (symbols 'back 'forward)
@@ -38,7 +38,7 @@
 
   ;; A history is a
   ;; (make-history string? (listof (cons/p symbol? string?))
-  ;;                       (union #f (listof (cons/p symbol? string?)))
+  ;;                       (or/c #f (listof (cons/p symbol? string?)))
   (define-struct history (k-url bindings headers))
 
   ;; Go over the input list, resuming the servlet on each choice, until the
@@ -102,7 +102,7 @@
         ((l) (resumer (history/list l r)))
         ((? null?) r))))
 
-  ;; history/list : (union (list/p (xexpr? . -> . string?)
+  ;; history/list : (or/c (list/p (xexpr? . -> . string?)
   ;;                               (listof (cons/p symbol? string?)))
   ;;                       (list/p (xexpr? . -> . string?)
   ;;                               (listof (cons/p symbol? string?))
@@ -150,7 +150,7 @@
       (else #f)))
 
   ;; Produce the k-url used for the next part of the form
-  ;; (xexpr/callback? . -> . (union false? string?))
+  ;; (xexpr/callback? . -> . (or/c false? string?))
   (define-syntax hyperlink->k-url
     (syntax-rules ()
       ((_ str)
diff --git a/collects/web-server/util.ss b/collects/web-server/util.ss
index a21fc88221..f3b55ca79b 100644
--- a/collects/web-server/util.ss
+++ b/collects/web-server/util.ss
@@ -17,13 +17,13 @@
    [valid-port? (any/c . -> . boolean?)]
    [decompose-request ((request?) . ->* . (url? symbol? string?))]
    [network-error ((symbol? string?) (listof any/c) . ->* . (void))]
-   [path->list  (path? . -> . (cons/c (union path? (symbols 'up 'same))
-                                      (listof (union path? (symbols 'up 'same)))))]
-   [url-path->path ((union (symbols 'up 'same) path?) string? . -> . path?)]
+   [path->list  (path? . -> . (cons/c (or/c path? (symbols 'up 'same))
+                                      (listof (or/c path? (symbols 'up 'same)))))]
+   [url-path->path ((or/c (symbols 'up 'same) path?) string? . -> . path?)]
    [directory-part (path? . -> . path?)]
-   [lowercase-symbol! ((union string? bytes?) . -> . symbol?)]
-   [exn->string ((union exn? any/c) . -> . string?)]
-   [build-path-unless-absolute (path? (union string? path?) . -> . path?)])
+   [lowercase-symbol! ((or/c string? bytes?) . -> . symbol?)]
+   [exn->string ((or/c exn? any/c) . -> . string?)]
+   [build-path-unless-absolute (path? (or/c string? path?) . -> . path?)])
   
   ;; valid-port? : any/c -> boolean?
   (define (valid-port? p)
@@ -61,13 +61,13 @@
              (apply format (format "~a: ~a" src fmt) args))
             (current-continuation-marks))))
   
-  ;; build-path-unless-absolute : path (union string? path?) -> path?
+  ;; build-path-unless-absolute : path (or/c string? path?) -> path?
   (define (build-path-unless-absolute base path)
     (if (absolute-path? path)
         (build-path path)
         (build-path base path)))
   
-  ;; exn->string : (union exn any) -> string
+  ;; exn->string : (or/c exn any) -> string
   (define (exn->string exn)
     (if (exn? exn)
         (parameterize ([current-error-port (open-output-string)])
@@ -75,7 +75,7 @@
           (get-output-string (current-error-port)))
         (format "~s\n" exn)))
   
-  ; lowercase-symbol! : (union string bytes) -> symbol
+  ; lowercase-symbol! : (or/c string bytes) -> symbol
   (define (lowercase-symbol! s)
     (let ([s (if (bytes? s)
                  (bytes->string/utf-8 s)